RajendranNair Deepthi Sreerengam, Karunakaran Jayakumar, Nair Renuka R
Division of Cellular and Molecular Cardiology, Sree ChitraTirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, 695011, India.
Department of Cardiovascular and Thoracic Surgery, SreeChitraTirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, 695011, India.
Mol Cell Biochem. 2017 Aug;432(1-2):109-122. doi: 10.1007/s11010-017-3002-4. Epub 2017 Apr 6.
Cardiac stem cells reside in niches where the oxygen levels are close to 3%. For cytotherapy, cells are conventionally expanded in ambient oxygen (21% O) which represents hyperoxia compared to the oxygen tension of niches. Cardiosphere-derived cells (CDCs) are then transplanted to host tissue with lower-O levels. The high-O gradient can reduce the efficacy of cultured cells. Based on the assumption that minimizing injury due to O gradients will enhance the yield of functionally efficient cells, CDCs were cultured in 3% O and compared with cells maintained in ambient O. CDCs were isolated from human right atrial explants and expanded in parallel in 21 and 3% oxygen and compared with regard to survival, proliferation, and retention of stemness. Increased cell viability even in the tenth passage and enhanced cardiosphere formation was observed in cells expanded in 3% O. The cell yield from seven passages was fourfold higher for cells cultured in 3% O. Preservation of stemness in hypoxic environment was evident from the proportion of c-kit-positive cells and reduced myogenic differentiation. Hypoxia promoted angiogenesis and reduced the tendency to differentiate to noncardiac lineages (adipocytes and osteocytes). Mimicking the microenvironment at transplantation, when shifted to 5% O, viability and proliferation rate were significantly higher for CDCs expanded in 3% O. Expansion of CDCs, from atria in sub-physiological oxygen, helps in obtaining a higher yield of healthy cells with better preservation of stem cell characteristics. The cells so cultured are expected to improve engraftment and facilitate myocardial regeneration.
心脏干细胞存在于氧含量接近3%的微环境中。对于细胞治疗，细胞通常在环境氧（21% O₂）中扩增，与微环境的氧张力相比，这代表高氧状态。然后将心球衍生细胞（CDC）移植到氧含量较低的宿主组织中。高氧梯度会降低培养细胞的功效。基于将氧梯度造成的损伤降至最低将提高功能高效细胞产量的假设，将CDC在3% O₂中培养，并与在环境氧中培养的细胞进行比较。从人右心房外植体中分离出CDC，并分别在21%和3%氧气中平行扩增，比较其存活、增殖和干性维持情况。在3% O₂中扩增的细胞即使在传代十次时仍具有更高的细胞活力，且心球形成增强。在3% O₂中培养的细胞七代的细胞产量比其他细胞高四倍。从c-kit阳性细胞比例及减少的肌源性分化可明显看出低氧环境中干性的保留。低氧促进血管生成，并降低向非心脏谱系（脂肪细胞和骨细胞）分化的倾向。模拟移植时的微环境，当转移到5% O₂时，在3% O₂中扩增的CDC的活力和增殖率显著更高。在亚生理氧条件下从心房扩增CDC，有助于获得更高产量的健康细胞，并更好地保留干细胞特性。如此培养的细胞有望改善植入并促进心肌再生。
