Storage effect on viability and biofunctionality of human adipose tissue-derived stromal cells

Strategies for the hypothermic preservation of cell sheets of human adipose stem cells

Cell Sheet (CS) Engineering is a regenerative medicine strategy proposed for the treatment of injured or diseased organs and tissues. In fact, several clinical trials are underway using CS-based methodologies. However, the clinical application of such cell-based methodologies poses several challenges related with the preservation of CS structure and function from the fabrication site to the bedside. Pausing cells at hypothermic temperatures has been suggested as a valuable method for short-term cell preservation. In this study, we tested the efficiency of two preservation strategies, one using culture medium supplementation with Rokepie and the other using the preservation solution Hypothermosol, in preserving human adipose stromal/stem cells (hASC) CS-like confluent cultures at 4°C, during 3 and 7 days. Both preservation strategies demonstrated excellent ability to preserve cell function during the first 3 days in hypothermia, as demonstrated by metabolic activity results and assessment of extracellular matrix integrity and differentiation potential. At the end of the 7^th day of hypothermic incubation, the decrease in cell metabolic activity was more evident for all conditions. Nonetheless, hASC incubated with Rokepie and Hypothermosol retained a higher metabolic activity and extracellular matrix integrity in comparison with unsupplemented cells. Differentiation results for the later time point showed that supplementation with both Rokepie and Hypothermosol rescued adipogenic differentiation potential but only Rokepie was able to preserve hASC osteogenic potential.

A Comparison of the Preservation of Mouse Adipose Tissue-Derived Mesenchymal Stem Cells Using the University of Wisconsin Solution and Hank's Balanced Salt Solution

Preservation of adipose tissue before the isolation of cells is one of the most important steps in maintaining the cell viability of adipose tissue-derived mesenchymal stem cells (ADSCs) for clinical use. Hank's balanced salt solution (HBSS) is one of the main ADSC preservation solutions used clinically. However, this step is known to lead to decreased cell viability. The University of Wisconsin (UW) solution is recognized by transplant physicians as an excellent organ preservation solution. We aimed to investigate the effectiveness of UW solution in preservation of the viability of ADSCs. We collected adipose tissue from the inguinal fat pad of mice and compared preservation in UW solution and HBSS overnight by measuring cell viability after isolation. We found that the number of viable cells harvested per gram of adipose tissue mass was higher in UW solution- than HBSS-preserved tissue.

Culture expansion of adipose derived stromal cells. A closed automated Quantum Cell Expansion System compared with manual flask-based culture

Background

Adipose derived stromal cells (ASCs) are a rich and convenient source of cells for clinical regenerative therapeutic approaches. However, applications of ASCs often require cell expansion to reach the needed dose. In this study, cultivation of ASCs from stromal vascular fraction (SVF) over two passages in the automated and functionally closed Quantum Cell Expansion System (Quantum system) is compared with traditional manual cultivation.

Methods

Stromal vascular fraction was isolated from abdominal fat, suspended in α-MEM supplemented with 10% Fetal Bovine Serum and seeded into either T75 flasks or a Quantum system that had been coated with cryoprecipitate. The cultivation of ASCs from SVF was performed in 3 ways: flask to flask; flask to Quantum system; and Quantum system to Quantum system. In all cases, quality controls were conducted for sterility, mycoplasmas, and endotoxins, in addition to the assessment of cell counts, viability, immunophenotype, and differentiation potential.

Results

The viability of ASCs passage 0 (P0) and P1 was above 96%, regardless of cultivation in flasks or Quantum system. Expression of surface markers and differentiation potential was consistent with ISCT/IFATS standards for the ASC phenotype. Sterility, mycoplasma, and endotoxin tests were consistently negative. An average of 8.0 × 10⁷ SVF cells loaded into a Quantum system yielded 8.96 × 10⁷ ASCs P0, while 4.5 × 10⁶ SVF cells seeded per T75 flask yielded an average of 2.37 × 10⁶ ASCs—less than the number of SVF cells seeded. ASCs P1 expanded in the Quantum system demonstrated a population doubling (PD) around 2.2 regardless of whether P0 was previously cultured in flasks or Quantum, while ASCs P1 in flasks only reached a PD of 1.0. Conclusion: Manufacturing of ASCs in a Quantum system enhances ASC expansion rate and yield significantly relative to manual processing in T-flasks, while maintaining the purity and quality essential to safe and robust cell production. Notably, the use of the Quantum system entails significantly reduced working hours and thereby costs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-1080-9) contains supplementary material, which is available to authorized users.