In Situ Normoxia Enhances Survival and Proliferation Rate of Human Adipose Tissue-Derived Stromal Cells without Increasing the Risk of Tumourigenesis

Abstract

Adipose tissue-derived stromal cells (ASCs) natively reside in a relatively low-oxygen tension (i.e., hypoxic) microenvironment in human body. Low oxygen tension (i.e., in situ normoxia), has been known to enhance the growth and survival rate of ASCs, which, however, may lead to the risk of tumourigenesis. Here, we investigated the tumourigenic potential of ASCs under their physiological condition to ensure their safe use in regenerative therapy. Human ASCs isolated from subcutaneous fat were cultured in atmospheric O2 concentration (21% O2) or in situ normoxia (2% O2). We found that ASCs retained their surface markers, tri-lineage differentiation potential, and self-renewal properties under in situ normoxia without altering their morphology. In situ normoxia displayed a higher proliferation and viability of ASCs with less DNA damage as compared to atmospheric O2 concentration. Moreover, low oxygen tension significantly up-regulated VEGF and bFGF mRNA expression and protein secretion while reducing the expression level of tumour suppressor genes p16, p21, p53, and pRb. However, there were no significant differences in ASCs telomere length and their relative telomerase activity when cultured at different oxygen concentrations. Collectively, even with high proliferation and survival rate, ASCs have a low tendency of developing tumour under in situ normoxia. These results suggest 2% O2 as an ideal culture condition for expanding ASCs efficiently while maintaining their characteristics.

Adipose-Derived Stromal Cells from Lipomas: Isolation, Characterisation and Review of the Literature

“…Apoptosis represents a process of programmed cell death [60.] It has been proposed that cellular apoptosis is not enhanced in lipoma, suggesting that the enlargement of lipoma tissue may be due to a positive balance of adipocyte turnover (accelerated adipogenesis combined with non-enhanced apoptosis) [41].…”

Chondrogenic potential of physically treated bovine cartilage matrix derived porous scaffolds on human dermal fibroblast cells

“…Mechanical cues (stiffness and strain) play important role in directing stem cell differentiation, suggesting their potential impact on chondrogenesis of HDFs as well . Also chondrogenesis has been shown to be enhanced under hypoxic condition . The future works can be performed under different culture conditions, for example, with mechanical stimulation (stiffness and strain) and hypoxia.…”

“…Cell viability. Cell viability at days 2,8,15,22,29,35,42 was determined using LIVE/DEADV R Viability/Cytotoxicity Kit (Invitrogen, UK). One lL of Calcein AM (4 mM in anhydrous DMSO) added to 2.5 lL of Ethidium homodimer (2 mM in DMSO/H 2 O 1:4 (V/V) (Molecular probes V R -Lifetechnologies TM , USA) were diluted in 1 mL pre-warmed 378C PBS.…”

Expansion and Adipogenesis Induction of Adipocyte Progenitors from Perivascular Adipose Tissue Isolated by Magnetic Activated Cell Sorting

“…It is important to note that APC yield can be affected by the animal’s age or size and by changes in the temperature of media and failure to maintain a sterile isolation environment. Culturing cells in normoxia is also important for proliferation and differentiation 19 , thus maintenance of incubation air conditions is integral to culture practice. Centrifugation speeds can be increased to 800 × g if sufficient cell pellets do not form during the isolation process.…”