Implantation of Inferior Vena Cava Interposition Graft in Mouse Model

Podsumowanie

To improve our knowledge of cellular and molecular neotissue formation, a murine model of the TEVG was recently developed. The grafts were implanted as infrarenal vena cava interposition grafts in C57BL/6 mice. This model achieves similar results to those achieved in our clinical investigation, but over a far shortened time-course.

Streszczenie

Biodegradable scaffolds seeded with bone marrow mononuclear cells (BMCs) are often used for reconstructive surgery to treat congenital cardiac anomalies. The long-term clinical results showed excellent patency rates, however, with significant incidence of stenosis. To investigate the cellular and molecular mechanisms of vascular neotissue formation and prevent stenosis development in tissue engineered vascular grafts (TEVGs), we developed a mouse model of the graft with approximately 1 mm internal diameter. First, the TEVGs were assembled from biodegradable tubular scaffolds fabricated from a polyglycolic acid nonwoven felt mesh coated with ε-caprolactone and L-lactide copolymer. The scaffolds were then placed in a lyophilizer, vacuumed for 24 hr, and stored in a desiccator until cell seeding. Second, bone marrow was collected from donor mice and mononuclear cells were isolated by density gradient centrifugation. Third, approximately one million cells were seeded on a scaffold and incubated O/N. Finally, the seeded scaffolds were then implanted as infrarenal vena cava interposition grafts in C57BL/6 mice. The implanted grafts demonstrated excellent patency (>90%) without evidence of thromboembolic complications or aneurysmal formation. This murine model will aid us in understanding and quantifying the cellular and molecular mechanisms of neotissue formation in the TEVG.

Wprowadzenie

Congenital heart defects are serious conditions that affect nearly 8% of live births in the United States. Approximately 25% of those infants with congenital heart defects or 2.4 per 1,000 live birth, require invasive treatment in the first year of their life¹. The most effective treatment for congenital heart disease is reconstructive surgery. Unfortunately, complications arising from the use of currently available vascular conduits are the most significant cause of postoperative morbidity and mortality.

To address this problem, we developed the first tissue engineered vascular grafts (TEVGs) for clinical use². TEVGs ....

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Protokół

NOTE: All animal procedures were approved by the Nationwide Children's Hospital Institutional Animal Care and Use Committee.

1. Graft Manufacturing

1. Make the ε-caprolactone and L-lactide copolymer P(LA/CL) solution by adding 100mg P(LA/CL) in 2 ml dioxane under a fume hood. Place the solution on a vortex and mix continuously for 1-1.5 hr to dissolve completely. 
2. In the meantime, remove a sheet of polyglycolic acid (PGA) felt from the freezer and cut out several 5 x 8 mm sections. Also cut off the tip of a 0.1-10 µl pipette just above the filter.
3. Insert a 19 G needle (1.5 length) into th....

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Wyniki

A schematic of TEVG implantation is shown in Figure 1. Bone marrow was harvested from a donor mouse and mono nuclear cells were isolated using density centrifugation and then seeded onto a biodegradable scaffold. The seeded scaffolds were incubated O/N and implanted to a recipient mouse as an inferior vena cava interposition graft.

Figure 2 illustrates the scanning electron microscopy of the PGA-P(CL/LA) scaffold. The internal diameter was approximately 1 mm a.......

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Dyskusje

The mouse model of TEVG is a valuable tool to study cellular and molecular mechanisms of neotissue formation and the development of stenosis. The seeded BM-MNC was shown in both histological and SEM images of the seeded cells on the graft¹¹. Cell seeding efficiency was also shown using a DNA assay⁷. Using this model system we showed that cell seeding reduces the incidence of the development of TEVG stenosis, which was the primary mode of failure in our human clinical trial³. The seeded ce.......

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Materiały

Name	Company	Catalog Number	Comments
Polyglycolic acid (PGA) felt	Biomedical Structures		Custome ordered
Pipet tip, 0.1-10 μl	Fisher Sientific	02-707-456
Lyophilizer	Labconco	7070020
RPMI medium 1604	Gibco	11875-093
Petri dish	BD	353003
24-well plate	Corning	3526
15 cc tube	BD	352096
Ficoll	Sigma	10831-100ml	Also called 'Histopaque'
DPBS	Gibco	14190-144
Littauer bone cutter 4.5" Straight	Roboz	RS-8480	For BM harvesting
Forceps 4.5"	Roboz	RS-8120	For BM harvesting
Scissors 4.5"	Roboz	RS-5912	For BM harvesting
Microscope	Leica	M80
C57BL/6J (H-2b), Female	Jackson Laboratories	664	8-12 weeks
Ketamine hydrochloride injection	Hospira Inc.	NDC 0409-2053
Xylazine sterile solution	Akorn Inc.	NADA# 139-236
Ketoprofen	Fort Dodge Animal Health	NDC 0856-4396-01
Ibuprofen	PrecisionDose	NDC 68094-494-59
Heparin sodium	Sagent Pharmaceticals	NDC 25021-400
Saline solution (sterile 0.9% sodium chloride)	Hospira Inc.	NDC 0409-0138-22
0.9% Sodium chloride injection	Hospira Inc.	NDC 0409-4888-10
Petrolatum ophthalmic ointment	Dechra Veterinary Products	NDC 17033-211-38
Iodine prep pads	Triad Disposables, Inc.	NDC 50730-3201-1
Alcohol prep pads	McKesson Corp.	NDC 68599-5805-1
Cotton tipped applicators	Fisher Scientific	23-400-118
Fine scissor	FST	14028-10
Micro-adson forcep	FST	11018-12
Clamp applying forcep	FST	00072-14
S&T Vascular clamp	FST	00396-01
Spring scissors	FST	15008-08
Colibri retractors	FST	17000-04
Dumont #5 forcep	FST	11251-20
Dumont #7 - fine forceps	FST	11274-20
Dumont #5/45 forceps	FST	11251-35
Tish needle holder/forceps	Micrins	MI1540
Black polyamide monofilament suture, 10-0	AROSurgical Instruments Corporation	TI638402	For suturing the graft
Black polyamide monofilament suture, 6-0	AROSurgical Instruments	SN-1956	For musculature and skin closure
Non-woven sponges	McKesson Corp.	94442000
Absorbable hemostat	Ethicon	1961
1 ml Syringe	BD	309659
3 ml Syringe	BD	309657
10 ml Syringe	BD	309604
18 G 1.5 in, Needle	BD	305190
25 G 1 in, Needle	BD	305125
30 G 1 in, Needle	BD	305106
Warm water recirculator	Gaymar	TP-700
Warming pad	Gaymar	TP-22G
Trimmer	Wahl	9854-500