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GROWTH FACTORS AND CYTOKINES USED IN CELL THERAPY MANUFACTURING
INTRODUCTION
Qualification of reagents, source materials, and control of the manufacturing process are key elements that ensure the quality and safety of cell therapies. Growth factors and cytokines are important for the maintenance, growth, selection, and purification of cultures of cell therapy products. This chapter describes the accepted tests, procedures, and acceptance criteria for growth factors and cytokines that may be involved in the manufacturing of cell therapy products.
RECOMBINANT HUMAN INTERLEUKIN 4 (rhIL-4)
| MHKCDITLQE | IIKTLNSLTE | QKTLCTELTV | TDIFAASKNT |
| TEKETFCRAA | TVLRQFYSHH | EKDTRCLGAT | AQQFHRHKQL |
| IRFLKRLDRN | LWGLAGLNSC | PVKEANQSTL | ENFLERLKTI |
| MREKYSKCSS |
| C658H1071N193O197S8 | 15,096 Da |
rhIL-4 is a single-chain polypeptide of 130 amino acid residues expressed in Escherichia coli. It is produced as a lyophilized powder and contains NLT 0.5 × 107 USP Units of IL-4/mg of total protein. Process specific host-cell DNA impurities in IL-4 with limits of less than 1 ng/mg are determined as described in Nucleic Acid-Based Techniques—Approaches for Detecting Trace Nucleic Acids (Residual DNA Testing) 1130. Neither manufacturing license nor market approval is required for IL-4 intended for use as an ancillary material during manufacturing. Following are typical IL-4 quality attributes.
1130. Neither manufacturing license nor market approval is required for IL-4 intended for use as an ancillary material during manufacturing. Following are typical IL-4 quality attributes.IDENTIFICATION
• A.
Amino-terminal sequence analysis of at least eight amino acids is performed with an automated sequencer, as described in Biotechnology-Derived Articles 1045. Stepwise-released phenylthiohydantoin amino acids are identified with on-line reversed-phase high-performance liquid chromatography, on the basis of their elution times.
1045. Stepwise-released phenylthiohydantoin amino acids are identified with on-line reversed-phase high-performance liquid chromatography, on the basis of their elution times.
• B.
Use the electrophoresis method followed by western blotting analysis to visualize the IL-4 protein. The method is sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), described in the test for Purity.
Phosphate buffered saline; Laemmli sample buffer, reducing; and Laemmli sample buffer, nonreducing:
Proceed as directed in the test for Purity in the Assay.
Standard stock solution:
50 µg/mL of reconstituted USP rHuman Interleukin 4 RS in Phosphate buffered saline. [Note—Do not agitate while mixing; swirl gently. ]
Standard solution:
20 µg/mL of IL-4, from Standard stock solution, in Phosphate buffered saline
Standard solution, reducing:
Combine 20 µL of Standard solution and 5 µL of Laemmli sample buffer, reducing.
Standard solution, nonreducing:
Combine 20 µL of Standard solution and 5 µL of Laemmli sample buffer, nonreducing.
Sample stock solution:
50 µg/mL of reconstituted IL-4 in Phosphate buffered saline. [Note—Do not agitate while mixing; swirl gently. ]
Sample solution:
20 µg/mL of IL-4, from Sample stock solution, in Phosphate buffered saline
Sample solution, reducing:
Combine 20 µL of Sample solution and 5 µL of Laemmli sample buffer, reducing.
Sample solution, nonreducing:
Combine 20 µL of Sample solution and 5 µL of Laemmli sample buffer, nonreducing.
Analysis
Samples:
Standard solution, reducing; Standard solution, nonreducing; Sample solution, reducing; and Sample solution, nonreducing
Western blotting:
After electrophoresis, the proteins are transferred onto a polyvinylidene fluoride (PVDF) membrane using standard procedures. Incubate the membrane for 1 h at room temperature with Phosphate buffered saline containing 0.1% Tween 20 and 5% skim milk powder. The membrane is then incubated with an anti-IL-4 antibody1 (diluted appropriately in Phosphate buffered saline), followed by incubation with a secondary antibody at room temperature under gentle agitation for 1 h for each of the antibodies. The IL-4 protein band is identified by developing the membrane using a suitable detection system.2
Acceptance criteria:
The developed Western blot should give a positive signal equivalent to the USP rHuman Interleukin 4 RS.
ASSAY
• Purity:
[Note—Purity is determined on the bulk material. ] SDS-PAGE is performed as described under Biotechnology-Derived Articles—Polyacrylamide Gel Electrophoresis 1056 under reducing and nonreducing conditions.
1056 under reducing and nonreducing conditions.
Molecular weight marker:
Use a suitable molecular weight marker containing protein bands between 10 and 200 kDa.
Phosphate buffered saline:
2.67 mM of potassium chloride, 1.47 mM of potassium phosphate (KH2PO4), 137.93 mM of sodium chloride, and 8.06 mM of dibasic sodium phosphate in water. Adjust to a pH of 7.0–7.3.
Laemmli sample buffer, nonreducing:
100 mM TRIS-HCl, pH 6.8, 50% glycerol, 0.25% bromophenol blue indicator, and 10% sodium lauryl sulfate in water
Laemmli sample buffer, reducing:
Add 2.5 µL mercaptoethanol to 50 µL of Laemmli sample buffer, nonreducing.
Sample stock solution:
400 µg/mL of bulk IL-4 in Phosphate buffered saline
Sample solution 1:
Combine 20 µL of Sample stock solution and 5 µL of Laemmli sample buffer, nonreducing.
Sample solution 2:
Combine 20 µL of Sample stock solution and 5 µL of Laemmli sample buffer, reducing.
Control A stock solution:
4 µg/mL of IL-4, from Sample stock solution, in Phosphate buffered saline. [Note—Control A solutions are run in triplicates in both reducing and nonreducing conditions. ]
Control A solution 1:
Combine 20 µL of Control A stock solution and 5 µL of Laemmli sample buffer, nonreducing.
Control A solution 2:
Combine 20 µL of Control A stock solution and 5 µL of Laemmli sample buffer, reducing.
Control B stock solution:
12 µg/mL of IL-4, from Sample stock solution, in Phosphate buffered saline. [Note—Control B solutions are run in duplicates in both reducing and nonreducing conditions. ]
Control B solution 1:
Combine 20 µL of Control B stock solution and 5 µL of Laemmli sample buffer, nonreducing.
Control B solution 2:
Combine 20 µL of Control B stock solution and 5 µL of Laemmli sample buffer, reducing.
Electrophoretic conditions
Mode:
Discontinuous PAGE gel
Stacking gel:
4% acrylamide
Resolving gel:
12% acrylamide
Run conditions:
10 min at 100 V; then 30 min at 200 V
Protein detection:
Silver stain
Analysis
Samples:
Sample solution 1, Sample solution 2, Control A solution 1, Control A solution 2, Control B solution 1, and Control B solution 2
Incubate 25 µL of each Sample solution and Control solution under nonreducing conditions for 5 min at 60
, and load onto the gel. Incubate 20 µL of each Sample solution and Control solution under reducing conditions for 5 min at 60, and load onto the gel. After silver staining and scanning the whole gel, determine the intensity of all detectable protein bands by densitometry, and calculate the percentage of each detectable protein band, in the Sample solution, twice by comparing the pixel intensity of each contaminating band with the mean value of Control solutions A and B, respectively, by the formulas:
, and load onto the gel. Incubate 20 µL of each Sample solution and Control solution under reducing conditions for 5 min at 60, and load onto the gel. After silver staining and scanning the whole gel, determine the intensity of all detectable protein bands by densitometry, and calculate the percentage of each detectable protein band, in the Sample solution, twice by comparing the pixel intensity of each contaminating band with the mean value of Control solutions A and B, respectively, by the formulas: Result = (A100) × 1/(A1) and
Result = (A100) × 3/(A3)
| A100 | = | = intensity of one contaminating band of the Sample solution |
| A1 | = | = mean intensity of all detectable bands of Control A solution |
| A3 | = | = mean intensity of all detectable bands of Control B solution |
IL-4 control solutions analysis should yield one detectable band with an apparent molecular weight of approximately 15 kDa. If values calculated by means of Control A solution are different from those revealed by comparison with Control B solution, the value corresponding to the highest amount of impurity should be taken. If the intensity of one of the contaminating bands is lower than the value of Control A solution (corresponding to 1%), the value of this contamination is set to 1%. The purity of the sample solution is then calculated:
Result = 100 – S Cn
| C | = | = percentage of each contamination given in rounded whole numbers |
| n | = | = number of contaminants of the IL-4 Sample solution |
Acceptance criteria:
The purity of IL-4 is NLT 97%, as determined by SDS-PAGE.
• Protein Content:
[Note—Protein content is determined on the basis of the packaged product. ]
Phosphate buffered saline:
Proceed as directed in the test for Purity.
Sample solution:
50 µg/mL of IL-4 in Phosphate buffered saline. [Note—Do not agitate while mixing; swirl gently. ]
Blank:
Phosphate buffered saline
Spectrometric conditions
Mode:
UV
Pathlength:
1 cm
Analytical wavelength:
280 nm
Analysis
Samples:
Sample solution and Blank
Calculate the protein concentration:
C = A280/0.63
| C | = | = IL-4 concentration of the Sample solution (mg/mL) |
| A280 | = | = absorbance at 280 nm |
SPECIFIC TESTS
• Bioidentity:
[Note—The biological activity measurement is determined on the basis of the packaged product. ]
RPMI 1640 medium with l-glutamine:
Prepare a mixture of the ingredients in the quantities shown in sufficient water to obtain 1 L of medium, and sterilize by filtration:
| Material | Quantity |
|---|---|
| Calcium nitrate (Ca(NO3)·4H2O) | 100 mg |
| Magnesium sulfate (MgSO4·7H2O) | 100 mg |
| Potassium chloride | 400 mg |
| Sodium chloride | 6000 mg |
| Sodium phosphate, dibasic anhydrous | 800 mg |
| Sodium bicarbonate | 2000 mg |
| Glycine | 10 mg |
| l-Arginine | 200 mg |
| l-Asparagine | 50 mg |
| l-Aspartic acid | 20 mg |
| l-Polyvinylidene fluoride l-cystine dihydrochloride | 20 mg |
| l-Glutamic acid | 20 mg |
| l-Glutamine | 300 mg |
| l-Histidine | 15 mg |
| l-Hydroxyproline | 20 mg |
| l-Isoleucine | 50 mg |
| l-Leucine | 50 mg |
| l-Lysine hydrochloride | 40 mg |
| l-Methionine | 15 mg |
| l-Phenylalanine | 15 mg |
| l-Proline | 20 mg |
| l-Serine | 30 mg |
| l-Threonine | 20 mg |
| l-Tryptophan | 5 mg |
| l-Tyrosine disodium salt dihydrate | 20 mg |
| l-Valine | 20 mg |
| Biotin | 0.2 mg |
| Choline chloride | 3 mg |
| d-Calcium pantothenate | 0.25 mg |
| Folic acid | 1 mg |
| i-Inositol | 35 mg |
| Niacinamide | 1 mg |
| para-Aminobenzoic acid | 1 mg |
| Pyridoxine hydrochloride | 1 mg |
| Riboflavin | 0.2 mg |
| Thiamine hydrochloride | 1 mg |
| Vitamin B12 | 0.005 mg |
| d-Glucose (dextrose) | 2000 mg |
| Glutathione (reduced) | 1 mg |
| Phenol red | 5 mg |
Growth medium:
Using aseptic procedures, prepare the following tissue culture medium:
Sterilize by filtration, and store at between 2 to 8. Use within 1 month. Add GM-CSF immediately before use.
| RPMI-1640 with l-glutamine | 500 mL |
| Sodium pyruvate 100 mM | 5 mL |
| Fetal bovine serum | 50 mL |
| Human rGM-CSFa | 3 × 104 International Units |
|
a
Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) is added extemporaneously.
|
|
to 8. Use within 1 month. Add GM-CSF immediately before use.
Assay medium:
Use Growth medium containing no GM-CSF.
Phosphate buffered saline:
Proceed as directed in the test for Purity in the Assay.
Resazurin solution:
11 mg of resazurin in 100 mL of Phosphate buffered saline. [Note—Sterile filter and store solution protected from light at 4. Resazurin solution is stable for at least 6 months if treated under sterile conditions. ]
. Resazurin solution is stable for at least 6 months if treated under sterile conditions. ]
[Note—For all Standard and Sample solutions, IL-4 concentration is determined by photometry at 280 nm using an extinction coefficient (
) of 0.63 mg
1cm1. ]
) of 0.63 mg1cm1. ]
Standard stock solution:
50 µg/mL of USP rHuman Interleukin 4 RS in Phosphate buffered saline. [Note—Do not agitate while mixing; swirl gently. ]
Standard solutions:
36, 12, 4, 1.33, 0.44, 0.15, 0.05, 0.016, 0.006 ng/mL of IL-4, from Standard stock solution in Assay medium
Sample stock solution:
50 µg/mL of IL-4 in Phosphate buffered saline. [Note—Do not agitate while mixing; swirl gently. ]
Sample solutions:
36, 12, 4, 1.33, 0.44, 0.15, 0.05, 0.016, 0.006 ng/mL of IL-4, from Sample stock solution in Assay medium
Control solution:
Use the Assay medium.
Cell culture preparation:
Prepare cell cultures of the human factor-dependent TF-1 cell line (ATCC No. CRL-2003), following the protocol described in the ATCC information sheet. Passage the cultures every 2–3 days, using 1:3 subcultures of the cells for up to 1 month. Seed density should be 0.5 × 106 cells/mL, and maximal density should be 3 × 106 cells/mL. Viability of the cells should be >90%. Maximal passage number is 24, and maximal cultivation time from thawing is 28 days. After 28 days, initiate a new culture. Cells are propagated using Growth medium at 37, supplemented with air and 5% carbon dioxide.
, supplemented with air and 5% carbon dioxide.
Analysis
Samples:
Standard solutions, Sample solutions, and Control solution
The activity of the Sample solution is determined in duplicate. Wash the cells three times in Phosphate buffered saline. Plate 2 × 104 TF-1 cells resuspended in 100 µL of Assay medium per well in 96-well, flat-bottom microplates. Incubate for 72 h at 37 and 5% CO2 atmosphere in a humidified incubator in the presence or absence of various concentrations of Standard solution, Sample solution, or Control solution by adding 100 µL of the corresponding solution to each well. Add 30 µL of Resazurin solution to each well and incubate for another 24 h. Determine the fluorescence intensity per well by reading the plate with a microplate reader using 544 nm (excitation) and 590 nm (emission). Convert the fluorescence intensity in each well to a percentage of the maximum fluorescence intensity. For the Sample solution and Standard solution, plot the percentage of fluorescence intensity versus the concentration of the respective solution. By using the least squares method of regression analysis, compute the ED50 in ng/mL of the Sample solution and the Standard solution. The coefficient of determination for curve regression should be 
0.98. Calculate the potency in USP Interleukin 4 Units/mg:
and 5% CO2 atmosphere in a humidified incubator in the presence or absence of various concentrations of Standard solution, Sample solution, or Control solution by adding 100 µL of the corresponding solution to each well. Add 30 µL of Resazurin solution to each well and incubate for another 24 h. Determine the fluorescence intensity per well by reading the plate with a microplate reader using 544 nm (excitation) and 590 nm (emission). Convert the fluorescence intensity in each well to a percentage of the maximum fluorescence intensity. For the Sample solution and Standard solution, plot the percentage of fluorescence intensity versus the concentration of the respective solution. By using the least squares method of regression analysis, compute the ED50 in ng/mL of the Sample solution and the Standard solution. The coefficient of determination for curve regression should be 0.98. Calculate the potency in USP Interleukin 4 Units/mg: Result = A × ES/EU
| A | = | = activity of USP rHuman Interleukin 4 RS (USP units/mg) |
| ES | = | = determined ED50 of Standard solution (ng/mL) |
| EU | = | = determined ED50 of Sample solution (ng/mL) |
Acceptance criteria:
NLT 0.5 × 107 USP IL-4 Units/mg
• Sterility Tests 71:
Meets the requirements
71:
Meets the requirements
• Bacterial Endotoxins Test 85:
It contains NMT 50 USP Endotoxin Units/mg.
85:
It contains NMT 50 USP Endotoxin Units/mg.
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight containers, and store at 80.
80.
• Labeling:
Material is of recombinant DNA origin.
1
A suitable anti-IL-4 antibody can be obtained from commercial sources (e.g., Dianova Inc.).
2
A suitable detection system can be obtained from commercial sources (e.g., Pierce/Perbio Science).
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| General Chapter | Rebecca C. Potts, Ph.D.
Assistant Science And Standards Liaison (301) 816-8567 |
(GCBA2010) General Chapters - Biological Analysis |
| 71 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison (301) 816-8339 |
(GCM2010) General Chapters - Microbiology |
| 85 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison (301) 816-8339 |
(GCM2010) General Chapters - Microbiology |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP38–NF33 Page 172
Pharmacopeial Forum: Volume No. 35(4) Page 915