Name: nutrient regulation by continuous feeding for large-scale expansion of mammalian cells in spheroids
Uploaded: 2016-09-25T13:00:00
Description: Watch this Scientific Journal Video about Nutrient Regulation by Continuous Feeding for Large-scale Expansion of Mammalian Cells in Spheroids at JoVE.com

The authors thank Michael Garwood and Sam Stein for their helpful comments, and Kristen M. Maynard for assistance with manuscript preparation.

1. Cell Line and Maintenance
<ol>
	<li>Obtain &#946;-TC6 cells (or other desired adherent mammalian cell line). In preparation for the study, culture, passage, and cryopreserve the cells according to provider instructions.</li>
</ol>
2. Assemble the Continuous Feeding System
NOTE: The continuous feeding system design in the method below was based on similar systems described in literature17&#8211;19,21,47&#8211;49. ...

Generating mammalian cell products for the production of biological agents and for cell therapies requires the culture and monitoring of mammalian cells in large scale55&#8211;58. Further, these applications call for defined and validated culture conditions. Simply increasing the volume of cells using research technologies will not meet all of these requirements. Manual medium changes causing fluctuations in nutrients and buildup of waste products reduce cell quality, viability and yield....

In order to generate large numbers of viable and functional human cells for transplantation, regulation of the culture conditions is imperative. Depletion of nutrients, along with buildup of metabolic waste are major contributors to senescence and metabolic changes that reduce the quality of the cell product1&#8211;3. This procedure demonstrates a method to culture mammalian cells in spheroids using a stirred bioreactor combined with an adjusted rate perfusion feeding system to regulate glucose in a physiological range4 throughout the duration of the culture. For the purpose of these studies, the physiological range was defined as between 100 and 200 mg/dl. The same methods can be used to regulate other nutrients and metabolic wastes such as lactate.
Static cultures in small volumes (1 - 30 ml) are typically used in the laboratory setting to maintain and differentiate cell lines for experimental purposes. Cell passaging is performed with complete medium changes as needed at regular intervals. Most &#8220;conventional&#8221; culture medium has a high glucose concentration (450 mg/dl for DMEM used in these studies) to allow for less frequent medium changes without the risk of nutrient limitations. However, this batch-feeding method still requires frequent manipulation, introduces variability in the cell environment, and increases the risk of contamination5&#8211;9. Stirred suspension bioreactors (SSB) provide better mixing and decreased handling3,10&#8211;20, but like static cultures, require manual medium changes that contribute to potentially damaging fluctuations in nutrient and waste product levels. Perfusion feeding of SSB cultures reduces these problems by continuous infusion and removal of medium, but large changes in nutrient levels due to cell growth remain an issue. The use of an adjusted feeding rate from calculations of nutrient usage based on estimated cell requirements can provide the stable cell environment required to optimize cell viability and function21&#8211;24.
There is a large body of literature describing methods for scalable SSB cultures of mammalian cells specifically for culture and expansion of pluripotent cells25&#8211;32, with others focused on islet (beta) cells17,33,34, or production of biological products24,35&#8211;38. Many of these investigated cell types may be grown in spheroid cultures, and specific procedures for the cell type being used should be optimized prior to implementing a continuous feeding system. In this demonstration, a perfusion feeding method was used to expand a beta cell line grown as spheroids in a stirred bioreactor39&#8211;43. The method described herein provides a straightforward implementation of feeding rate adjustments based on off-line glucose measurements to achieve targeted culture conditions. Adjusting the feed rate with this method to maintain a physiological glucose level is shown to increases cell yields. Mammalian cells are dependent on a key nutrient, glucose, for energy production, so the use of this cell line represents a model for many cultured mammalian cells44. In addition, this line exemplifies the further complexity of beta cells, which are sensitive to chronic high levels of glucose45. For this study, &#946;-TC6 cells were allowed to form spheroids in culture to approximate the average size of islets of Langerhans in vivo. The perfusion bioreactor system17&#8211;19,21,46 with a feed rate adjusted to glucose consumption, resulted in maintaining physiological conditions and higher cell yields without changes in viability.

<table border="0" cellpadding="0" cellspacing="0" width="840">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:271px;">Name of Reagent/ Equipment</td>
			<td style="width:249px;">Company</td>
			<td style="width:153px;">Catalog Number / Link</td>
			<td style="width:167px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">BTC-6 Cells</td>
			<td style="width:249px;">ATCC, Manassas, VA</td>
			<td style="width:153px;">CRL-11506</td>
			<td>Mouse Insulinoma cell line (adherent cell type)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">DPBS No CA, No Mg</td>
			<td style="width:249px;">Invitrogen, Carlsbad, CA</td>
			<td style="width:153px;">14190-144</td>
			<td><a href="https://www.lifetechnologies.com/order/catalog/product/14190144?ICID=search-14190144">https://www.lifetechnologies.com/order/catalog/product/14190144?ICID=search-14190144</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Dulbecco&#39;s Modified Eagles Medium</td>
			<td style="width:249px;">Invitrogen, Carlsbad, CA</td>
			<td style="width:153px;"></td>
			<td>See below for product numbers&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">DMEM High Glucose (500mM)</td>
			<td style="width:249px;">Invitrogen, Carlsbad, CA</td>
			<td>11965-092</td>
			<td><a href="http://www.lifetechnologies.com/order/catalog/product/11965092">http://www.lifetechnologies.com/order/catalog/product/11965092</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">DMEM Low Glucose (100mM)</td>
			<td style="width:249px;">Invitrogen, Carlsbad, CA</td>
			<td>11885-084</td>
			<td><a href="http://www.lifetechnologies.com/order/catalog/product/11885084%20(note%20that%20this%20medium%20already%20contains%20pyruvate)">http://www.lifetechnologies.com/order/catalog/product/11885084 (note that this medium already contains pyruvate)</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">L-gultamine</td>
			<td style="width:249px;">Invitrogen, Carlsbad, CA</td>
			<td style="width:153px;">25030081</td>
			<td><a href="http://www.lifetechnologies.com/order/catalog/product/25030081?ICID=search-product">http://www.lifetechnologies.com/order/catalog/product/25030081?ICID=search-product</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Sodium Pyruvate</td>
			<td style="width:249px;">Invitrogen, Carlsbad, CA</td>
			<td style="width:153px;">11360070</td>
			<td><a href="https://www.lifetechnologies.com/order/catalog/product/11360070?ICID=search-product">https://www.lifetechnologies.com/order/catalog/product/11360070?ICID=search-product</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Heat Inactivated Porcine Serum</td>
			<td style="width:249px;">Gibco - Life Technologies</td>
			<td style="width:153px;">10082147</td>
			<td><a href="http://www.lifetechnologies.com/order/catalog/product/10082147">http://www.lifetechnologies.com/order/catalog/product/10082147</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Trypsin-EDTA</td>
			<td style="width:249px;">Invitrogen, Carlsbad, CA</td>
			<td style="width:153px;">25200056</td>
			<td><a href="https://www.lifetechnologies.com/order/catalog/product/25200056?ICID=search-product">https://www.lifetechnologies.com/order/catalog/product/25200056?ICID=search-product</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">T-150 Tissue Culture Treated Flasks</td>
			<td style="width:249px;">Corning, Corning, NY</td>
			<td style="width:153px;">430825</td>
			<td><a href="http://catalog2.corning.com/LifeSciences/en-US/Shopping/ProductDetails.aspx?productid=430825(Lifesciences)&amp;categoryname=">http://catalog2.corning.com/LifeSciences/en-US/Shopping/ProductDetails.aspx?productid=430825(Lifesciences) 
			&#38;categoryname=</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NuAire Cell culture incubator</td>
			<td style="width:249px;">Princeton, MN</td>
			<td style="width:153px;"></td>
			<td>US Autoflow , Any water-jacketed CO2 regulating cell culture incubator could be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Centrifuge</td>
			<td style="width:249px;"></td>
			<td style="width:153px;"></td>
			<td>Sorvall RT 7 (Any similar benchtop centrifuge may be used)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Refrigerator</td>
			<td style="width:249px;"></td>
			<td style="width:153px;"></td>
			<td>Any laboratory refrigerator could be used (a small table-top version was used for these studies)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">1L Glass Bottle</td>
			<td style="width:249px;">Corning, Corning, NY</td>
			<td style="width:153px;">1395-1L</td>
			<td>Any vendor could be used http://catalog2.corning.com/LifeSciences/en-US/Shopping/ProductDetails.aspx?productid=1395-1L(Lifesciences) 
			&#38;categoryname=</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">2L Glass Bottle</td>
			<td style="width:249px;">Corning, Corning, NY</td>
			<td style="width:153px;">1395-2L</td>
			<td>Any vendor could be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">250 ml stirred bioreactors&#160;</td>
			<td style="width:249px;">Corning, Corning, NY</td>
			<td style="width:153px;">4500-250</td>
			<td><a href="http://catalog2.corning.com/LifeSciences/en-US/Shopping/ProductDetails.aspx?productid=4500-250(Lifesciences)&amp;categoryname=">http://catalog2.corning.com/LifeSciences/en-US/Shopping/ProductDetails.aspx?productid=4500-250(Lifesciences) 
			&#38;categoryname=</a></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Stir Plate</td>
			<td style="width:249px;">Fisher Scientific</td>
			<td style="width:153px;">11-496-104A</td>
			<td>Any incubator safe stir-plate can be used, any vendor</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:271px;">Tissue Culture Dishes 100mm Diameter</td>
			<td style="width:249px;">Nunc, Rochester, NY (Fisher Scientific)</td>
			<td style="width:153px;">1256598&#160;</td>
			<td>Any vendor could be used (ordered through Fisher Sci)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">FALCON 50 ml Conical Tubes</td>
			<td style="width:249px;">Falcon, San Jose, CA</td>
			<td style="width:153px;">1256598</td>
			<td>Any vendor could be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Delran Plastic Used for Custom Parts</td>
			<td style="width:249px;">McMaster Carr</td>
			<td style="width:153px;">Various</td>
			<td>Any material of choice could be used, but Deran is chosen because it is autoclave safe, non-reactive, and easy to machine, http://www.mcmaster.com/#acetal-homopolymer-sheets/=rjrcac</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Stainless Steel Pipe for custom lids</td>
			<td style="width:249px;">McMaster Carr</td>
			<td style="width:153px;">Various</td>
			<td>Any vendor could be used, http://www.mcmaster.com/#standard-stainless-steel-tubing/=rjrd91</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:271px;">Custom Modified Delran Bioreactor Lids for Continuous Feeding</td>
			<td style="width:249px;">Custom made&#160;</td>
			<td style="width:153px;"></td>
			<td>Not aware of any vendors producing a similar product</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:271px;">Custom Modified Glass Bottle Lids for Continuous feeding</td>
			<td style="width:249px;">Custom made&#160;</td>
			<td style="width:153px;"></td>
			<td>Some vendors (eg. Fischer Sci, Corning) make similar products in the links below</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Masterflex Digital Peristaltic Pump</td>
			<td style="width:249px;">Cole Parmer, Vernon Hills, IL</td>
			<td style="width:153px;">EW-77919-25</td>
			<td>Any precision peristaltic pump could be used, http://www.coleparmer.com/Product/L_S_Eight_Channel_Four_Roller_ 
			Cartridge_Pump_System_115_230 
			_VAC/EW-77919-25</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">PVDF Tubing Connectors (various)</td>
			<td style="width:249px;">Cole Parmer, Vernon Hills, IL</td>
			<td style="width:153px;">see link</td>
			<td>Any vendor could be used, http://www.coleparmer.com/Category/Cole_Parmer_PVDF_Premium 
			_Luer_Fittings/55889</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Pharmed BPT Tubing L/S 16</td>
			<td style="width:249px;">Cole Parmer, Vernon Hills, IL</td>
			<td style="width:153px;">WU-06508-16</td>
			<td>Any vendor could be used, http://www.coleparmer.com/Product/Masterflex_PharMed_BPT_Tubing 
			_L_S_13_25/WU-06508-16</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Pharmed BPT Tubing L/S 14</td>
			<td style="width:249px;">Cole Parmer, Vernon Hills, IL</td>
			<td style="width:153px;">WU-06508-14</td>
			<td>Any vendor could be used, http://www.coleparmer.com/Product/Masterflex_PharMed_BPT_Tubing 
			_L_S_13_25/WU-06508-14</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Pharmed BPT Tubing L/S 13</td>
			<td style="width:249px;">Cole Parmer, Vernon Hills, IL</td>
			<td style="width:153px;">WU-06508-13</td>
			<td>Any vendor could be used, http://www.coleparmer.com/Product/Masterflex_PharMed_BPT_Tubing 
			_L_S_13_25/WU-06508-13</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:271px;">Millipore Millex GP PES membrane 0.22ul sterile syringe filter (used for venting, and medium filtration)</td>
			<td style="width:249px;">Fisher Scientific</td>
			<td style="width:153px;">SLGP033RS</td>
			<td>Any vendor could be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">25ml Graduated Pipette</td>
			<td style="width:249px;">Fisher Scientific</td>
			<td style="width:153px;">13-678-11</td>
			<td>Any vendor could be used, and various sizes may be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Pipetter</td>
			<td style="width:249px;">Fisher Scientific</td>
			<td style="width:153px;">13-681-15E</td>
			<td>Any vendor, or similar product could be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Hemocytometer</td>
			<td style="width:249px;">Fisher Scientific</td>
			<td style="width:153px;">02-671-6</td>
			<td>Any vendor, or similar product could be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Trypan Blue</td>
			<td style="width:249px;">Gibco - Life Technologies</td>
			<td style="width:153px;">15250-061</td>
			<td>Any vendor, or similar product could be used, https://www.lifetechnologies.com/order/catalog/product/15250061</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Inverted Light Microscope</td>
			<td style="width:249px;">Leica</td>
			<td style="width:153px;"></td>
			<td>Any vendor, or similar product could be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">One Touch Ultra Blood Glucose Meter</td>
			<td style="width:249px;">Fisher Scientific</td>
			<td style="width:153px;">22-029-293&#160;</td>
			<td>Any vendor, or similar product could be used (eg. Bayer)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">One Touch Ultra-Strips</td>
			<td style="width:249px;">Fisher Scientific</td>
			<td style="width:153px;">22-029-292&#160;</td>
			<td>Any vendor, or similar product could be used (eg. Bayer)</td>
		</tr>
	</tbody>
</table>

nutrient regulation by continuous feeding for large-scale expansion of mammalian cells in spheroids

In this demonstration, spheroids formed from the &#946;-TC6 insulinoma cell line were cultured as a model of manufacturing a mammalian islet cell product to demonstrate how regulating nutrient levels can improve cell yields. In previous studies, bioreactors facilitated increased culture volumes over static cultures, but no increase in cell yields were observed. Limitations in key nutrients such as glucose, which were consumed between batch feedings, can lead to limitations in cell expansion. Large fluctuations in glucose levels were observed, despite the increase in glucose concentrations in the media. The use of continuous feeding systems eliminated fluctuations in glucose levels, and improved cell growth rates when compared with batch fed static and SSB culture methods. Additional increases in growth rates were observed by adjusting the feed rate based on calculated nutrient consumption, which allowed the maintenance of physiological glucose over three weeks in culture. This method can also be adapted for other cell types.

Medium Glucose Levels and Fluctuations Restrict Cell Expansion in Standard SSB Cultures
Glucose levels fluctuate in static cultures and SSB cultures throughout the culture period3. These fluctuations intensify with increasing cell number during the 21-day culture period and were nearly identical in both static and SSB cultures. These observations are presented in our previous publication3. The glucose levels can be super-physiological for the duration of ...

Watch this Scientific Journal Video about Nutrient Regulation by Continuous Feeding for Large-scale Expansion of Mammalian Cells in Spheroids at JoVE.com

Nutrient Regulation by Continuous Feeding for Large-scale Expansion of Mammalian Cells in Spheroids

Nutrient regulation using continuous growth adjusted feeding improves growth rates of mammalian cell spheroids compared to intermittent batch feeding for cultures in stirred suspension bioreactors. This study demonstrates the methods required for establishing simple adjusted rate fed cultures.

In this demonstration, spheroids formed from the &#946;-TC6 insulinoma cell line were cultured as a model of manufacturing a mammalian islet cell product ...

The overall goal of this process is to culture large number of cells under controlled nutrient conditions. Using conventional equipment found in a cell culture laboratory. The associated algorithms allow the control and manipulation of nutrients within experimental ranges.This method can help answer key questions for large scale cell culture applications. Such as human cellular therapies. The main advantage of this technique is that is facilities culture of cells in large scale with uniform distribution of nutrients and gases.This allows higher cell densities than static or bulk fed cell cultures, increases yield, and reduces cell loss. This can be done with equipment commonly found in most cell culture laboratories. Visual demonstration of this method may be helpful to new investigators as these techniques used can be difficult to master, due to the large number of steps that must be preformed in a specific order under sterile conditions.Collect the five primary components needed for the feeding system. A medium reservoir, peristaltic pump, stirred bioreactor, waste reservoir, and custom designed tubing sampling set. Establish the medium reservoir using a one liter glass bottle.The waste reservoir using a two liter glass bottle. The stirred bioreactor using a 250mL volume glass reactor. Use a digital peristaltic pump, or similar pump with a eight channel pump head to control medium exchange.Assemble the reservoir and modified bioreactor lids from hard and autoclavable plastic. With stainless steel pipe pass-through ports to provide ventilation through sterile filters, and allow for medium transfer between reservoirs and bioreactors. Attach an outflow tube fabricated from porous glass aeration tubes to the modified stirred suspension bioreactor lid.Assemble autoclavable perfusion tubing sets from polyvinylidene fluoride tubing connectors, and durable peristaltic pump tubing. The length of the section is dependent on the distance between the different components. Assemble the feed line using two tubing diameters.Use L/S 14 for the primary tubing that will span the distance from the bioreactor to the medium reservoir. Insert a sort length of L/S 13 tubing in the middle of the tubing length for the pump section, using the appropriate PVDF adapters. Use standard PVDF hose-barbed tubing adapters to join two pieces of L/S 14 tubing on either side of the shorter pump section tubing.Assemble the section tubing section for waste removal using larger diameter L/S 16 tubing, and insert a short section of L/S 14 tubing in the middle for the pumping section. This is done in the same way as the feed line assembly using PVDF hose-barbed adapters. Assemble the final component of the tubing set by constructing the set from three short L/S 14 tubing lengths.Connected together with a T-type HVDF connector, and two small hose clamps on two of the tubing lengths. Connect the sample assembly to the stainless steel sample connector attached on the lid of the bioreactor. After sterilization, a sterile gas filter will be attached for gas venting to one of the clamped lengths.The other is used for connection to a sterile sampling syringe. Autoclave the sampling assembly while it is connected to the bioreactor, prior to beginning the experiment as described in the text protocol. Use this assembly to collect sterile samples from the bioreactor as needed, without disturbing the continuous feed process.Attach sterile vents to the appropriate locations on the lids of the spinner flask, the medium vessel, waste vessels, and sample ports. Culture and harvest the cells as described in the text protocol. Allow the cells to incubate at room temperature in trypsin for two to three minutes in a biosafety cabinet, and then collect them into a conical tube.A small cell sample is then collected and stained with trypan blue. Count the cell density using a microscope and standard hemocytometer with trypan blue staining as described in the text protocol. Add the desired number of total cells to sterile stirred suspension bioreactors for each condition.Add the medium to the stirred suspension bioreactor using a pipette to reach the desired total culture volume. Move the stirred suspension bioreactor with cells to a stir plate inside a cell culture incubator. Culture cells in the bioreactors without feeding for three days at 37 degrees Celsius, with 5%carbon dioxide, 100%relative humidity, and a stir rate of 70 rpm to allow spheroids to form.After spheroid formation remove the stirred suspension bioreactor from the incubator. Assemble the components for the continuous feeding system in a biological safety cabinet. First fill a fresh medium reservoir with the desired culture medium and then connect to one side of the feed line.Also ensure that the fresh medium reservoir is properly vented with a sterile filter. A sterile filter should be replaced on the bioreactor inlet port to filter the medium before it enters the bioreactor. Connect the waste line to the medium waste reservoir and ensure that the waste reservoir is properly vented with a sterile filter.Put the stirred suspension bioreactor onto the stir plate inside of the incubator using the same culture parameters as for spheroid formation. Put the fresh medium reservoir inside a nearby mini-refrigerator. Ensure that the feed lines are able to exit the refrigerator without preventing the doors from closing.It is also critical that the feed lines are not pinched closed by the doors of either the refrigerator or the incubator. The waste medium reservoir can be put on the bench top outside the incubator in a convenient location. Pass the remaining tubing ends into the incubator and connect the feed line to the filter on the inlet port of the bioreactor.Then connect the waste line to the outflow tube port. Next place the pump section of the feed and waste lines into the pump head, ensuring the proper orientation so that the feed lines will pump medium from the fresh medium reservoir into the stirred suspension bioreactor, and the waste lines will pump medium from the bioreactor, and to the waste medium reservoir. Calculate the feed rate using the adjusted feed rate equation as described in the text protocol.Use the most recent sample with cell count information, along with the growth rate prediction and the medium glucose measurements to estimate the feed rate needed to maintain the desired glucose concentration in the culture. Set the pump speed based on the calculated feed rate. Repeat the feed rate calculation and adjust the pump speed for each sampling point.Medium glucose measurements are shown from Beta-TC6 insulinoma spheroid cultures using static stirred suspension bioreactors, and continuously fed stirred suspension bioreactor culture methods. Feeding with standard high glucose medium. The continuous feeding is able to eliminate the glucose fluctuations, but the average glucose levels in the medium change dramatically during the culture period, and are far above the physiological range.The adjusted feeding is able to eliminate the fluctuations, as well as maintain the glucose concentrations near physiological levels for the duration of the culture period. Here cell growth reported as fold change in cell number during the 21 day culture period is compared for stirred suspension bioreactors with regular medium changes, constant feed rate stirred suspension bioreactor cultures, and adjusted feed rate stirred suspension bioreactor cultures. Following this procedure other methods like varying conditions cam be preformed in order to answer additional questions, like nutrient requirements for new cell lines, or specific experimental outcomes.After it's development, this technique paved the way for researchers in the field of cell biology to explore metabolic requirements in cells from humans with cancer or other disorders. After watching this video you should have a good understanding of how to assemble a profusion cell culture system to better control culture conditions and maximize cell yields. Don't forget that working with human cells can be extremely hazardous, and precautions such as protection from blood borne pathogens should always be taken while performing this procedure.

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We demonstrate the use of a simple microfluidic setup, in which single budding yeast cells can be tracked throughout their entire lifespan. The ...

Surgical Retrieval, Isolation and In vitro Expansion of Human Anterior Cruciate Ligament-derived Cells for Tissue Engineering Applications

Surgical Retrieval, Isolation and In vitro Expansion of Human Anterior Cruciate Ligament-derived Cells for Tissue Engineering Applications

Injury to the ACL is a commonly encountered problem in active individuals. Even partial tears of this intra-articular knee ligament lead to biomechanical ...

Luminescence Resonance Energy Transfer to Study Conformational Changes in Membrane Proteins Expressed in Mammalian Cells

Luminescence Resonance Energy Transfer, or LRET, is a powerful technique used to measure distances between two sites in proteins within the distance range ...

Cultivation of Mammalian Cells Using a Single-use Pneumatic Bioreactor System

Recent advances in mammalian, insect, and stem cell cultivation and scale-up have created tremendous opportunities for new therapeutics and personalized ...

Cloning and Large-Scale Production of High-Capacity Adenoviral Vectors Based on the Human Adenovirus Type 5

High-capacity adenoviral vectors (HCAdV) devoid of all viral coding sequences represent one of the most advanced gene delivery vectors due to their high ...

Culturing Mammalian Cells in Three-dimensional Peptide Scaffolds

A useful technique for culturing cells in a self-assembling nanofiber three-dimensional (3D) scaffold is described. This culture system recreates an ...

Detection of Endotoxin in Nano-formulations Using Limulus Amoebocyte Lysate (LAL) Assays

Detection of Endotoxin in Nano-formulations Using Limulus Amoebocyte Lysate LAL Assays

When present in pharmaceutical products, a Gram-negative bacterial cell wall component endotoxin (often also called lipopolysaccharide) can cause ...

Cultivating a Three-dimensional Reconstructed Human Epidermis at a Large Scale

A three-dimensional human epidermis model reconstructed from neonatal primary keratinocytes is presented. Herein, a protocol for the cultivation process ...

Reliably Engineering and Controlling Stable Optogenetic Gene Circuits in Mammalian Cells

Reliable gene expression control in mammalian cells requires tools with high fold change, low noise, and determined input-to-output transfer functions, ...