Effect of mild heat stress on the proliferative and differentiative ability of human mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) are an attractive candidate for autologous cell therapy, but regenerative potential can be compromised with extensive in vitro cell passaging. Development of viable cell therapies must address the effect of in vitro passaging to maintain overall functionality of expanded MSCs.We examined the effect of repeated mild heat shock on the proliferation and differentiation capability of human adipose-derived MSCs. Adipose tissue MSCs were characterized by means of fluorescence activated cell sorting analysis for expression of CD3, CD14, CD19, CD34, CD44, CD45, CD73, CD90 and CD105. Similarly, the expression of SIRT-1, p16(INK4a) and p21 was determined by means of polymerase chain reaction. Measurements of population doubling, doubling time and superoxide dismutase activity were also determined. Differentiation of expanded MSCs into bone and adipose were analyzed qualitatively and quantitatively.The strategy led to an increase in expression of SIRT-1 concomitant with enhanced viability, proliferation and delayed senescence. The stressed MSCs showed better differentiation into osteoblasts and adipocytes.The results indicate that mild heat shock could be used to maintain MSC proliferative and differentiation potential.