Name: subretinal transplantation of human embryonic stem cell-derived retinal tissue in a feline large animal model
Uploaded: 2021-08-05T13:00:00
Description: Watch this Scientific Journal Video about Subretinal Transplantation of Human Embryonic Stem Cell-Derived Retinal Tissue in a Feline Large Animal Model at JoVE.com

This work was funded by NEI Fast-track SBIR grant R44-EY027654-01A1&#160;and SBIR grant 3 R44 EY 027654 - 02 S1 (I.O.N., Lineage Cell Therapeutics; Dr. Petersen-Jones is a co-PI). The authors would like to thank Ms. Janice Querubin (MSU RATTS) for her help with anesthesia and general care for the animals included in this study as well as help with surgical setting and instruments preparation/sterilization. The authors would like to thank Dr. Paige Winkler for the help in receiving the organoids and placing them in media on the day prior to the implantation and for the help on the day of the implantation. The authors are also grateful to Mr. Randy Garchar (LCTX) for diligent shipping of retinal organoids, assembling the shipper, and downloading temperature and G-stress-records after each shipment. This work was performed while author Igor Nasonkin was employed by&#160;Biotime (now Lineage).

Procedures were conducted in compliance with the Association for Research in Vision and Ophthalmology (ARVO) statement for Use of Animals in Ophthalmic and Vision Research. They were also approved by the Michigan State University Institutional Animal Care and Use Committee. Wild-type and CrxRdy/+ cats from a colony of cats maintained at Michigan State University were used in this study. Animals were housed under 12 h : 12 h light-dark cycles and fed a commercial complete cat diet.
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Implantation of hPSC-derived retinal tissue (retinal organoids) into the subretinal space is a promising experimental approach for restoring vision for late-stage retinal degenerative diseases caused by PR cell death (profound or terminal blindness). The presented approach builds on an earlier developed and successfully tested experimental therapy based on subretinal grafting of a piece of human fetal retinal tissue23,24,25. It ...

Millions of people around the world are impacted by retinal degeneration (RD) with resulting visual impairment or blindness associated with loss of the light-sensing photoreceptors (PRs). Age-related macular degeneration (AMD) is a major cause of blindness resulting from a combination of genetic risk factors and environmental/lifestyle factors. In addition, over 200 genes and loci have been found to cause inherited RD (IRD)1. Retinitis pigmentosa (RP), the commonest IRD, is genetically heterogenous with more than 3,000 genetic mutations in approximately 70 genes being reported2,3,4. Leber Congenital Amaurosis (LCA), which causes blindness in childhood is also genetically heterogenous5,6. Gene augmentation therapy has been developed and is in clinical trials for treating a small number of IRDs3,7. However, a separate therapy must be developed for the treatment of each distinct genetic form of IRD and thereby only treating a small subset of patients. Furthermore, gene augmentation relies on the presence of a population of rescuable photoreceptors and is, therefore, not applicable for advanced degeneration.
There is, therefore, an urgent and yet unmet clinical need for the development of therapies addressing and treating advanced RDs and profound to terminal blindness. Over the last 2 decades neuroprosthetic implants have been developed and tested in large animal models, such as the cat, prior to human use8,9,10,11,12,13,14. Likewise, in the past 20 years retinal replacement therapies utilizing sheets of embryonic or even mature mammalian retina grafted subretinally have been developed15,16,17,18,19,20,21,22 and even tested successfully in RD patients23,24,25. Both approaches utilize the idea of introducing new sensors (photovoltaic silicon photodiodes in the case of neuroprosthetic devices26,27, and healthy mutation-free photoreceptors organized in sheets, in the case of retinal sheet implantation) into retina with degenerated PRs. Recent studies have investigated the use of stem cells-based approaches such as transplantation of human pluripotent stem cell (hPSC)-derived retinal progenitors28,29, hPSC-photoreceptors30, and hPSC-retinal organoids31,32,33. Retinal organoids enable the formation of retinal tissue in a dish and derivation of photoreceptor sheets with thousands of mutation-free PRs, which resemble the photoreceptor layer in the developing human fetal retina34,35,36,37,38,39,40. Transplanting hPSC-derived retinal tissue (organoids) into the subretinal space of patients with RD conditions is one of the new and promising investigational cell therapy approaches, being pursued by a number of teams31,32,41,42. Compared to transplantation of the cell suspension (of young photoreceptors or retinal progenitors), transplanted sheets of fetal photoreceptors were demonstrated to result in vision improvements in clinical trials23,24.
The protocol presented here describes, in detail, a transplantation procedure for subretinal delivery of the whole retinal organoids (rather than organoid rims33,41) as a potentially better way to introduce intact retinal sheets with PRs, to increase graft survival and improve the sheet preservation. Though procedures for introducing a flat piece of human retina and also RPE patches have been developed43,44,45, transplantation of larger 3D grafts has not been investigated. Stem cell-derived retinal organoids provide an inexhaustible source of photoreceptor sheets for developing vision restoration technologies, are free of ethical restriction, and are considered an excellent source of human retinal tissue for therapies focused on treating advanced RD and terminal blindness46. Development of surgical methods for precise subretinal implantation of retinal organoids with minimal injury to the host retinal niche (neural retina, retinal pigment epithelium and retinal and choroidal vasculature) is one of the critical steps for advancing such therapy toward clinical applications31,32. Large animal models such as cats, dogs, pigs, and monkeys have proven to be good models for investigating surgical delivery methods as well as to demonstrate the safety of implanted sheets of tissue (retinal pigment epithelium (RPE) cells) and investigate the use of organoids41,44,45,47,48,49,50. The large animal eye has a similar globe size to human as well as similar anatomy including the presence of a region of high photoreceptor density, including cones (the area centralis), resembling the human macula6,51,52.
In this manuscript, a technique for the implantation of hPSC-derived retinal tissue (organoids) into the subretinal space of feline large animal models (both wild-type and CrxRdy/+ cats) is described, which, together with promising efficacy results32,53 builds a foundation for further development of such investigational therapy toward clinical applications to treat RD conditions.

<table>
	<tbody>
		<tr>
			<td>0.22 &#181;m pore syringe filter with PES membrane</td>
			<td>Cameo</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>23G subretinal injector with extendable 41 G cannula</td>
			<td>DORC</td>
			<td>1270.EXT</td>
			<td></td>
		</tr>
		<tr>
			<td>250 &#181;L hamilton gas tight luer lock syringe</td>
			<td>Hamilton</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>6-0 Silk suture</td>
			<td>Ethicon</td>
			<td>707G</td>
			<td></td>
		</tr>
		<tr>
			<td>6-0/7-0 polyglactin suture</td>
			<td>Ethicon</td>
			<td>J570G</td>
			<td></td>
		</tr>
		<tr>
			<td>Acepromazine maleate 500mg/5mL (Aceproject)</td>
			<td>Henry Schein Animal Health</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>Buprenorphine 0.3 mg/mL</td>
			<td>Par Pharmaceutical</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>cSLO + SD-OCT</td>
			<td>Heidelberg Engineering</td>
			<td>Spectralis HRA+ OCT</td>
			<td></td>
		</tr>
		<tr>
			<td>Cyclosporine</td>
			<td>Novartis</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>Dexamethasone 2mg/mL (Azium)</td>
			<td>Vetone</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>Doxycyline 25mg/5mL</td>
			<td>Cipla</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>Fatal Plus solution (pentobarnital solution)</td>
			<td>Vortech</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>Gentamicin 20mg/2mL</td>
			<td>Hospira</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>Glass capillary (Thin-Wall Single-Barrel Standard Borosilicate (Schott Duran) Glass Tubing</td>
			<td>World Precision Instruments</td>
			<td>TW150-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Methylprednisolone actetate 40 mg/mL</td>
			<td>Pfizer</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Zeiss</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>OCT medium (Tissue-Tek O.C.T. Compound)</td>
			<td>Sakura</td>
			<td>4583</td>
			<td></td>
		</tr>
		<tr>
			<td>Olympic Vac-Pac Size 23</td>
			<td>Natus</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>Paraformaldehyde 16% solution</td>
			<td>EMS</td>
			<td>15719</td>
			<td></td>
		</tr>
		<tr>
			<td>Phenylephrine Hydrochloride 10% Ophthalmic Solution</td>
			<td>Akorn</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>Prednisolone 15mg/5mL</td>
			<td>Akorn</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>Propofol 5000mg/50mL (10 mg/mL) (PropoFlo28)</td>
			<td>Zoetis</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>RetCam II video fundus camera</td>
			<td>Clarity Medical Systems</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>Triamcinolone 400mg/10 mL (Kenalog-40)</td>
			<td>Bristol -Myers Squibb Company</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>Tropicamide 1% ophthalmic solution</td>
			<td>Akorn</td>
			<td>NA</td>
			<td>can be found by various suppliers</td>
		</tr>
		<tr>
			<td>Vitrectomy 23G port</td>
			<td>Alcon</td>
			<td>Accurus systems</td>
			<td></td>
		</tr>
		<tr>
			<td>Vitrectomy machine</td>
			<td>Alcon</td>
			<td>Accurus systems</td>
			<td></td>
		</tr>
		<tr>
			<td>Vitreo-retinal vertical 80&#176; scissors with squeeze handle</td>
			<td>Frimen</td>
			<td>FT170206T</td>
			<td></td>
		</tr>
	</tbody>
</table>

subretinal transplantation of human embryonic stem cell-derived retinal tissue in a feline large animal model

Retinal degenerative (RD) conditions associated with photoreceptor loss such as age-related macular degeneration (AMD), retinitis pigmentosa (RP) and Leber Congenital Amaurosis (LCA) cause progressive and debilitating vision loss. There is an unmet need for therapies that can restore vision once photoreceptors have been lost. Transplantation of human pluripotent stem cell (hPSC)-derived retinal tissue (organoids) into the subretinal space of an eye with advanced RD brings retinal tissue sheets with thousands of healthy mutation-free photoreceptors and has a potential to treat most/all blinding diseases associated with photoreceptor degeneration with one approved protocol. Transplantation of fetal retinal tissue into the subretinal space of animal models and people with advanced RD has been developed successfully but cannot be used as a routine therapy due to ethical concerns and limited tissue supply. Large eye inherited retinal degeneration (IRD) animal models are valuable for developing vision restoration therapies utilizing advanced surgical approaches to transplant retinal cells/tissue into the subretinal space. The similarities in globe size, and photoreceptor distribution (e.g., presence of macula-like region area centralis) and availability of IRD models closely recapitulating human IRD would facilitate rapid translation of a promising therapy to the clinic. Presented here is a surgical technique of transplanting hPSC-derived retinal tissue into the subretinal space of a large animal model allowing assessment of this promising approach in animal models.

This procedure enables the successful and reproducible implantation of hPSC-derived retinal organoids in the subretinal space of a large eye animal model (demonstrated here using 2 examples: wild-type cats with healthy photoreceptors (PRs) and CrxRdy/+ cats with degenerating PRs and retina). Using the steps indicated in Figure 1 prepare and load the hPSC-derived retinal organoids into the borosilicate glass cannula of the injection device so that the organoids ar...

Watch this Scientific Journal Video about Subretinal Transplantation of Human Embryonic Stem Cell-Derived Retinal Tissue in a Feline Large Animal Model at JoVE.com

Subretinal Transplantation of Human Embryonic Stem Cell-Derived Retinal Tissue in a Feline Large Animal Model

Presented here is a surgical technique for transplanting human pluripotent stem cell (hPSC)-derived retinal tissue into the subretinal space of a large animal model.

Retinal degenerative (RD) conditions associated with photoreceptor loss such as age-related macular degeneration (AMD), retinitis pigmentosa (RP) and ...

The current protocol shows in detail subretinal delivery of the whole retinal organoids in a large animal model, aiming at developing cell therapy approaches for retinal degeneration. The main advantage of this technique is that it allows for delivery of organoids directly to the target tissue, the retina. The technique aims to treat advanced blinding retinal degenerative conditions, such as age-related macular degeneration, retinitis pigmentosa, or leber congenital amaurosis.Demonstrating the procedure will be Dr.Peterson Jones. For subretinal implantation of the organoids, use Stevens Tenotomy Scissors to perform a 0.5 to 1 centimeter lateral canthotomy in a four-month-old overnight-fasted anesthetized cat, and place an appropriately sized Barraquer eyelid speculum into the incision to keep the eyelids open with a surgical assistant regularly irrigating the cornea with BSS throughout the procedure. Use 0.5 Castroviejo corneal tying forceps and a small mosquito hemostat to gently grasp the bulbar conjunctiva next to the limbus.Place two 6-0 silk sutures into the conjunctiva immediately adjacent to the limbus at the 4 and 8 o'clock positions to hold the eye in primary gaze and to retract the third eyelid. Clamp the ends of the sutures with small mosquito hemostats to help their manipulation, and place another suture at the 12 o'clock position at the limbus partially through the thickness of the limbus, taking care not to penetrate the eye. Loosely knot the suture, cutting the end short, and place a stay suture in the conjunctiva immediately adjacent to the limbus at the 4 o'clock position to hold the eye and primary gaze.Reflect the bulbar conjunctiva between 10 and 2 o'clock, and use tenotomy scissors to incise the conjunctiva two to three millimeters from the limbus. Undermine the conjunctiva and clear the Tenon's capsule to expose the sclera at the two and 10 o'clock vitrectomy port sites three to five millimeters from the limbus. Use calipers to identify the sites for sclerotomy, avoiding the major scleral vessels that can be prominent in the cat.Planning for a three millimeter region at the 10 o'clock instrument port for a right-handed surgeon, pre-place 6-0 or 7-0 polyglactin cruciate pattern sutures without tying at the sites of the proposed sclerotomies. Once the sutures are in place, have the assistant grasp the 12 o'clock stay sutures to help keep the globe in position, and use 0.12 millimeter Castroviejo forceps to hold the tissue next to the sclerotomy site. Uses a trocar to introduce a 23 gauge vitrectomy port through the sclera at both the 2 and 10 o'clock positions angled toward the optic nerve to avoid contacting the lens, and use tying forceps to gently push the irrigation port to determine whether the tips can be visualized within the vitreous.Have the assistant place a Machemer magnifying irrigating vitrectomy lens onto the cornea to allow visualization of the posterior segment of the eye, and a 23 gauge vitrectomy probe cutter through the instrument port to perform a partial core vitrectomy. Next, introduce the needle of a one milliliter syringe containing one milliliter of triamcinolone solution into the instrument port and inject 250 to 500 microliters of the crystal suspension. When the solution has been delivered, Advance the vitrectomy probe through the instrument port to close to the optic nerve head with the port facing away from the retinal surface.Use high vacuum to help detach the vitreal face from the retina, insert the injector through the instrument port toward the retinal surface, and extrude the cannula tip. Gently press the tip of the retinal surface and have the assistant to give a slight quick push on the syringe plunger to start the retinal detachment, reducing the injection pressure to permit a slow increase of the retinal detachment until the desired size is achieved. Use a 41 gauge cannula of the injector to slightly enlarge the detachment until retinal scissors can be introduced, and remove the 10 o'clock scleral port.Then use a straight 2.850 millimeter slit knife oriented toward the optic nerve to avoid touching the lens to enlarge the sclerotomy at this site. Make the retinotomy on the bleb away from the optic nerve to avoid damaging retinal nerve fibers originating from the transplanted region, and avoid cutting major retinal vessels to reduce the risk of hemorrhage. To implant the organoids, insert a glass capillary loaded with organoids through the enlarged sclerotomy toward the retinotomy site, and use the tip of the capillary to slightly open the retinotomy to allow access to the subretinal bleb opening.Have the assistant slowly press the plunger of the injector again to inject the organoids into the subretinal bleb. BSS should proceed organoids, the organs, and flush the retinotomy open. When all of the organoids have been delivered, leave the glass capillary in place for a few seconds before slowly removing the capillary from the eye, taking care to avoid any sudden release of fluid.When the capillary has been removed, close the sclerotomy using the pre-placed suture in a cruciate pattern. Have the assistant remove the infusion port, and quickly tie the sclerotomy suture and close the peritomy with the polyglactin sutures in a simple continuous pattern. Close the lateral canthotomy with a 6-0 polyglactin suture and figure-eight skin sutures to perform the lateral canthus and use simple interrupted skin sutures to close the rest of the wound.Then administer the appropriate post-surgical steroid and antibiotic cocktail. Human pluripotent stem cell-derived retinal organoid loading can be confirmed within the glass cannula of the injection device and during the surgery by direct visualization. The presence of the organoids within the subretinal space can be confirmed postoperatively by ophthalmic examination and fundus imaging.Prior to euthanasia, confocal scanning laser ophthalmoscopy and spectral domain optical coherence tomography imaging can also be performed to assess the position of the organoids. These techniques can be used to demonstrate the persistence of retinal organoids in the subretinal space between the neural retina and the retinal pigment epithelium of the recipient eye. Histological and immunohistochemical analyses can be used to illustrate the survival of the xenogeneic graphs within the subretinal space of a large eye in an immunosuppressed animal.Only those skilled in vitreoretinal surgery, such as trained veterinary ophthalmologists or vitreoretinal surgeons familiar with the species differences in the cat eye compared to human eye should undertake this procedure. The technique presented in this video should be applicable to other large animal models that are used for translating vitreoretinal surgical techniques to the clinics.

subretinal-transplantation-human-embryonic-stem-cell-derived-retinal

Research

JoVE Journal

Neuroscience

Efficient Derivation of Human Neuronal Progenitors and Neurons from Pluripotent Human Embryonic Stem Cells with Small Molecule Induction

There is a large unfulfilled need for a clinically-suitable human neuronal cell source for repair or regeneration of the damaged central nervous system (CNS) structure and circuitry in today's healthcare industry. Cell-based therapies hold great promise to restore the lost nerve tissue and function for CNS disorders. However, cell therapies based on CNS-derived neural stem cells have encountered supply restriction and difficulty to use in the clinical setting due to their limited expansion ability in culture and failing plasticity after extensive passaging1-3. Despite some beneficial outcomes, the CNS-derived human neural stem cells (hNSCs) appear to exert their therapeutic effects primarily by their non-neuronal progenies through producing trophic and neuroprotective molecules to rescue the endogenous cells1-3. Alternatively, pluripotent human embryonic stem cells (hESCs) proffer cures for a wide range of neurological disorders by supplying the diversity of human neuronal cell types in the developing CNS for regeneration1,4-7. However, how to channel the wide differentiation potential of pluripotent hESCs efficiently and predictably to a desired phenotype has been a major challenge for both developmental study and clinical translation. Conventional approaches rely on multi-lineage inclination of pluripotent cells through spontaneous germ layer differentiation, resulting in inefficient and uncontrollable lineage-commitment that is often followed by phenotypic heterogeneity and instability, hence, a high risk of tumorigenicity7-10. In addition, undefined foreign/animal biological supplements and/or feeders that have typically been used for the isolation, expansion, and differentiation of hESCs may make direct use of such cell-specialized grafts in patients problematic11-13. To overcome these obstacles, we have resolved the elements of a defined culture system necessary and sufficient for sustaining the epiblast pluripotence of hESCs, serving as a platform for de novo derivation of clinically-suitable hESCs and effectively directing such hESCs uniformly towards clinically-relevant lineages by small molecules14 (please see a schematic in Fig. 1). Retinoic acid (RA) does not induce neuronal differentiation of undifferentiated hESCs maintained on feeders1, 14. And unlike mouse ESCs, treating hESC-differentiated embryoid bodies (EBs) only slightly increases the low yield of neurons1, 14, 15. However, after screening a variety of small molecules and growth factors, we found that such defined conditions rendered retinoic acid (RA) sufficient to induce the specification of neuroectoderm direct from pluripotent hESCs that further progressed to neuroblasts that generated human neuronal progenitors and neurons in the developing CNS with high efficiency (Fig. 2). We defined conditions for induction of neuroblasts direct from pluripotent hESCs without an intervening multi-lineage embryoid body stage, enabling well-controlled efficient derivation of a large supply of human neuronal cells across the spectrum of developmental stages for cell-based therapeutics.

We have established a protocol for induction of neuroblasts direct from pluripotent human embryonic stem cells maintained under defined conditions with small molecules, which enables derivation of a large supply of human neuronal progenitors and neuronal cell types in the developing CNS for neural repair.

There is a large unfulfilled need for a clinically-suitable human neuronal cell source for repair or regeneration of the damaged central nervous system ...

Dissection, Culture, and Analysis of Xenopus laevis Embryonic Retinal Tissue

The process by which the anterior region of the neural plate gives rise to the vertebrate retina continues to be a major focus of both clinical and basic research. In addition to the obvious medical relevance for understanding and treating retinal disease, the development of the vertebrate retina continues to serve as an important and elegant model system for understanding neuronal cell type determination and differentiation1-16. The neural retina consists of six discrete cell types (ganglion, amacrine, horizontal, photoreceptors, bipolar cells, and M&uuml;ller glial cells) arranged in stereotypical layers, a pattern that is largely conserved among all vertebrates 12,14-18.
While studying the retina in the intact developing embryo is clearly required for understanding how this complex organ develops from a protrusion of the forebrain into a layered structure, there are many questions that benefit from employing approaches using primary cell culture of presumptive retinal cells 7,19-23. For example, analyzing cells from tissues removed and dissociated at different stages allows one to discern the state of specification of individual cells at different developmental stages, that is, the fate of the cells in the absence of interactions with neighboring tissues 8,19-22,24-33. Primary cell culture also allows the investigator to treat the culture with specific reagents and analyze the results on a single cell level 5,8,21,24,27-30,33-39. Xenopus laevis, a classic model system for the study of early neural development 19,27,29,31-32,40-42, serves as a particularly suitable system for retinal primary cell culture 10,38,43-45.
Presumptive retinal tissue is accessible from the earliest stages of development, immediately following neural induction 25,38,43. In addition, given that each cell in the embryo contains a supply of yolk, retinal cells can be cultured in a very simple defined media consisting of a buffered salt solution, thus removing the confounding effects of incubation or other sera-based products 10,24,44-45.
However, the isolation of the retinal tissue from surrounding tissues and the subsequent processing is challenging. Here, we present a method for the dissection and dissociation of retinal cells in Xenopus laevis that will be used to prepare primary cell cultures that will, in turn, be analyzed for calcium activity and gene expression at the resolution of single cells. While the topic presented in this paper is the analysis of spontaneous calcium transients, the technique is broadly applicable to a wide array of research questions and approaches (Figure 1).

Dissection, Culture, and Analysis of Xenopus laevis Embryonic Retinal Tissue

Xenopus laevis provides an ideal model system for studying cell fate specification and physiological function of individual retinal cells in primary cell culture. Here we present a technique for dissecting retinal tissues and generating primary cell cultures that are imaged for calcium activity and analyzed by in situ hybridization.

The process by which  the anterior region of the neural plate gives rise to the vertebrate retina  continues to be a major focus of both clinical and ...

Limbal Approach-Subretinal Injection of Viral Vectors for Gene Therapy in Mice Retinal Pigment Epithelium

The eye is a small and enclosed organ which makes it an ideal target for gene therapy. Recently various strategies have been applied to gene therapy in retinopathies using non-viral and viral gene delivery to the retina and retinal pigment epithelium (RPE). Subretinal injection is the best approach to deliver viral vectors directly to RPE cells. Before the clinical trial of a gene therapy, it is inevitable to validate the efficacy of the therapy in animal models of various retinopathies. Thus, subretinal injection in mice becomes a fundamental technique for an ocular gene therapy. In this protocol, we provide the easy and replicable technique for subretinal injection of viral vectors to experimental mice. This technique is modified from the intravitreal injection, which is widely used technique in ophthalmology clinics. The representative results of RPE/choroid/scleral complex flat-mount will help to understand the efficacy of this technique and adjust the volume and titer of viral vectors for the extent of gene transduction.

Subretinal injection is a surgical technique for effective gene delivery to retinal pigment epithelium in the mouse eye. Here we describe an easy and replicable method for subretinal injection of viral vectors to retinal pigment epithelium in experimental mice.

The eye is a small and enclosed organ which makes it an ideal target for gene therapy. Recently various strategies have been applied to gene therapy in ...

Development of a Refined Protocol for Trans-scleral Subretinal Transplantation of Human Retinal Pigment Epithelial Cells into Rat Eyes

Degenerative retinal diseases such as age-related macular degeneration (AMD) are the leading cause of irreversible vision loss worldwide. AMD is characterized by the degeneration of retinal pigment epithelial (RPE) cells, which are a monolayer of cells functionally supporting and anatomically wrapping around the neural retina. Current pharmacological treatments for the non-neovascular AMD (dry AMD) only slow down the disease progression but cannot restore vision, necessitating studies aimed at identifying novel therapeutic strategies. Replacing the degenerative RPE cells with healthy cells holds promise to treat dry AMD in the future. Extensive preclinical studies of stem cell replacement therapies for AMD involve the transplantation of stem cell-derived RPE cells into the subretinal space of animal models, in which the subretinal injection technique is applied. The approach most frequently used in these preclinical animal studies is through the trans-scleral route, which is made difficult by the lack of direct visualization of the needle end and can often result in retinal damage. An alternative approach through the vitreous allows for direct observation of the needle end position, but it carries a high risk of surgical traumas as more eye tissues are disturbed. We have developed a less risky and reproducible modified trans-scleral injection method that uses defined needle angles and depths to successfully and consistently deliver RPE cells into the rat subretinal space and avoid excessive retinal damage. Cells delivered in this manner have been previously demonstrated to be efficacious in the Royal College of Surgeons (RCS) rat for at least 2 months. This technique can be used not only for cell transplantation but also for delivery of small molecules or gene therapies.

Subretinal injection has been widely applied in preclinical studies of stem cell replacement therapy for age-related macular degeneration. In this visualized article, we describe a less risky, reproducible and precisely modified subretinal injection technique via the trans-scleral approach to deliver cells into rat eyes.

Degenerative retinal diseases such as age-related macular degeneration (AMD) are the leading cause of irreversible vision loss worldwide. AMD is ...

Modelling Zika Virus Infection of the Developing Human Brain In Vitro Using Stem Cell Derived Cerebral Organoids

The recent emergence of Zika virus (ZIKV) in susceptible populations has led to an abrupt increase in microcephaly and other neurodevelopmental conditions in newborn infants. While mosquitos are the main route of viral transmission, it has also been shown to spread via sexual contact and vertical mother-to-fetus transmission. In this latter case of transmission, due to the unique viral tropism of ZIKV, the virus is believed to predominantly target the neural progenitor cells (NPCs) of the developing brain.
Here a method for modeling ZIKV infection, and the resulting microcephaly, that occur when human cerebral organoids are exposed to live ZIKV is described. The organoids display high levels of virus within their neural progenitor population, and exhibit severe cell death and microcephaly over time. This three-dimensional cerebral organoid model allows researchers to conduct species-matched experiments to observe and potentially intervene with ZIKV infection of the developing human brain. The model provides improved relevance over standard two-dimensional methods, and contains human-specific cellular architecture and protein expression that are not possible in animal models.

Modelling Zika Virus Infection of the Developing Human Brain In Vitro Using Stem Cell Derived Cerebral Organoids

This protocol describes a technique used to model Zika virus infection of the developing human brain. Using wildtype or engineered stem cell lines, researchers may use this technique to uncover the various mechanisms or treatments that may affect early brain infection and resulting microcephaly in Zika virus-infected embryos.

The recent emergence of Zika virus (ZIKV) in susceptible populations has led to an abrupt increase in microcephaly and other neurodevelopmental conditions ...

Method for High Speed Stretch Injury of Human Induced Pluripotent Stem Cell-derived Neurons in a 96-well Format

Traumatic brain injury (TBI) is a major clinical challenge with high morbidity and mortality. Despite decades of pre-clinical research, no proven therapies for TBI have been developed. This paper presents a novel method for pre-clinical neurotrauma research intended to complement existing pre-clinical models. It introduces human pathophysiology through the use of human induced pluripotent stem cell-derived neurons (hiPSCNs). It achieves loading pulse duration similar to the loading durations of clinical closed head impact injury. It employs a 96-well format that facilitates high throughput experiments and makes efficient use of expensive cells and culture reagents. Silicone membranes are first treated to remove neurotoxic uncured polymer and then bonded to commercial 96-well plate bodies to create stretchable 96-well plates. A custom-built device is used to indent some or all of the well bottoms from beneath, inducing equibiaxial mechanical strain that mechanically injures cells in culture in the wells. The relationship between indentation depth and mechanical strain is determined empirically using high speed videography of well bottoms during indentation. Cells, including hiPSCNs, can be cultured on these silicone membranes using modified versions of conventional cell culture protocols. Fluorescent microscopic images of cell cultures are acquired and analyzed after injury in a semi-automated fashion to quantify the level of injury in each well. The model presented is optimized for hiPSCNs but could in theory be applied to other cell types.

Here we present a method for a human in vitro model of stretch injury in a 96-well format on a timescale relevant to impact trauma. This includes methods for fabricating stretchable plates, quantifying the mechanical insult, culturing and injuring cells, imaging, and high content analysis to quantify injury.

Traumatic brain injury (TBI) is a major clinical challenge with high morbidity and mortality. Despite decades of pre-clinical research, no proven ...

Transplantation of Human Induced Pluripotent Stem Cell-Derived Microglia in Immunocompetent Mice Brain via Non-Invasive Transnasal Route

Microglia are the specialized population of macrophage-like cells of the brain. They play essential roles in both physiological and pathological brain functions. Most of our current understanding of microglia is based on experiments performed in the mouse. Human microglia differ from mouse microglia, and thus response and characteristics of mouse microglia may not always represent that of human microglia. Further, due to ethical and technical difficulties, research on human microglia is restricted to in vitro culture system, which does not capitulate in vivo characteristics of microglia. To overcome these issues, a simplified method to non-invasively transplant induced pluripotent stem cell-derived human microglia (iPSMG) into the immunocompetent mice brain via a transnasal route in combination with pharmacological depletion of endogenous microglia using a colony-stimulating factor 1 receptor (CSF1R) antagonist is developed. This protocol provides a way to non-invasively transplant cells into the mouse brain and may therefore be valuable for evaluating the in vivo role of human microglia in physiological and pathological brain functions.

The protocol presented here allows the transplantation of induced pluripotent stem cell-derived human microglia (iPSMG) into the brain via a transnasal route in immunocompetent mice. The method for the preparation and transnasal transplantation of cells and the administration of cytokine mixture for the maintenance of iPSMG is shown.

Microglia are the specialized population of macrophage-like cells of the brain. They play essential roles in both physiological and pathological brain ...

Transplantation of Human Stem Cell-Derived GABAergic Neurons into the Early Postnatal Mouse Hippocampus to Mitigate Neurodevelopmental Disorders

A reduced number or dysfunction of inhibitory interneurons is a common contributor to neurodevelopmental disorders. Therefore, cell therapy using interneurons to replace or mitigate the effects of altered neuronal circuits is an attractive therapeutic avenue. To this end, more knowledge is needed about how human stem cell-derived GABAergic interneuron-like cells (hdINs) mature, integrate, and function over time in the host circuitry. Of particular importance in neurodevelopmental disorders is a better understanding of whether these processes in transplanted cells are affected by an evolving and maturing host brain. The present protocol describes a fast and highly efficient generation of hdINs from human embryonic stem cells based on the transgenic expression of the transcription factors Ascl1 and Dlx2. These neuronal precursors are transplanted unilaterally, after 7 days in vitro, to the hippocampus of neonatal 2-day-old mice. The transplanted neurons disperse in the ipsi- and contralateral hippocampus of a mouse model of cortical dysplasia-focal epilepsy syndrome and survive for up to 9 months after transplantation. This approach allows for investigating the cellular identity, integration, functionality, and therapeutic potential of transplanted interneurons over an extended time in developing healthy and diseased brains.

Transplantation of human pluripotent stem cell-derived GABAergic neurons generated by neuronal programming could be a potential treatment approach for neurodevelopmental disorders. This protocol describes the generation and transplantation of human stem cell-derived GABAergic neuronal precursors into the brains of neonatal mice, allowing long-term investigation of grafted neurons and evaluation of their therapeutic potential.

A reduced number or dysfunction of inhibitory interneurons is a common contributor to neurodevelopmental disorders. Therefore, cell therapy using ...

Organotypic Cultures of Adult Human Cortex as an Ex vivo Model for Human Stem Cell Transplantation and Validation

Neurodegenerative disorders are common and heterogeneous in terms of their symptoms and cellular affectation, making their study complicated due to the lack of proper animal models that fully mimic human diseases and the poor availability of post-mortem human brain tissue. Adult human nervous tissue culture offers the possibility to study different aspects of neurological disorders. Molecular, cellular, and biochemical mechanisms could be easily addressed in this system, as well as testing and validating drugs or different treatments, such as cell-based therapies. This method combines long-term organotypic cultures of the adult human cortex, obtained from epileptic patients undergoing resective surgery, and ex vivo intracortical transplantation of induced pluripotent stem cell-derived cortical progenitors. This method will allow the study of cell survival, neuronal differentiation, the formation of synaptic inputs and outputs, and the electrophysiological properties of human-derived cells after transplantation into intact adult human cortical tissue. This approach is an important step prior to the development of a 3D human disease modeling platform that will bring basic research closer to the clinical translation of stem cell-based therapies for patients with different neurological disorders and allow the development of new tools for reconstructing damaged neural circuits.

Organotypic Cultures of Adult Human Cortex as an Ex vivo Model for Human Stem Cell Transplantation and Validation

This protocol describes long-term organotypic cultures of adult human cortex combined with ex vivo intracortical transplantation of induced pluripotent stem cell-derived cortical progenitors, which present a novel methodology to further test stem cell-based therapies for human neurodegenerative disorders.

Neurodegenerative disorders are common and heterogeneous in terms of their symptoms and cellular affectation, making their study complicated due to the ...

Culturing Human Midbrain Dopaminergic Neurons for Phenotypic Profiling

Phenotypic Profiling of Human Stem Cell-Derived Midbrain Dopaminergic Neurons

Parkinson&#39;s disease (PD) is linked to a range of cell biological processes that cause midbrain dopaminergic (mDA) neuron loss. Many current in vitro PD cellular models lack complexity and do not take multiple phenotypes into account. Phenotypic profiling in human induced pluripotent stem cell (iPSC)-derived mDA neurons can address these shortcomings by simultaneously measuring a range of neuronal phenotypes in a PD-relevant cell type in parallel. Here, we describe a protocol to obtain and analyze phenotypic profiles from commercially available human mDA neurons. A neuron-specific fluorescent staining panel is used to visualize the nuclear, &#945;-synuclein, Tyrosine hydroxylase (TH), and Microtubule-associated protein 2 (MAP2) related phenotypes. The described phenotypic profiling protocol is scalable as it uses 384-well plates, automatic liquid handling and high-throughput microscopy. The utility of the protocol is exemplified using healthy donor mDA neurons and mDA neurons carrying the PD-linked G2019S mutation in the Leucine-rich repeat kinase 2 (LRRK2) gene. Both cell lines were treated with the LRRK2 kinase inhibitor PFE-360 and phenotypic changes were measured. Additionally, we demonstrate how multidimensional phenotypic profiles can be analyzed using clustering or machine learning-driven supervised classification methods. The described protocol will particularly interest researchers working on neuronal disease modeling or studying chemical compound effects in human neurons.

Author Spotlight: Generating Neuronal Phenotypic Profiles - A Protocol to Culture and Image Human Midbrain Dopaminergic Neurons 

This protocol describes the cell culturing of human midbrain dopaminergic neurons, followed by immunological staining and the generation of neuronal phenotypic profiles from acquired microscopic high-content images allowing the identification of phenotypic variations due to genetic or chemical modulations.

Parkinson&#39;s disease (PD) is linked to a range of cell biological processes that cause midbrain dopaminergic (mDA) neuron loss. Many current in vitro ...