Influence of age and pathological obesity on the potential use of human adipose-derived stem cells (hASCs) in orthopaedic tissue engineering

Human adipose stem cells (hASCs) show several features, such as a multi-differentiative potential and a reduced immunogenicity, that make them suitable candidates in tissue engineering for several applications in the orthopaedic field . We believe that it is important to define some factors that may influence the ability of hASCs to grow and osteo-differentiate and which could explain some inter-donor variabilities. In order to study the influence of age and the body mass index (BMI) we have isolated hASCs from abdominal subcutaneous adipose tissue aspirated from healthy younger females (n=12, mean age 31±4 years, BMI<30), from middle age ones (n=14, mean age 56 ±7 years, mean BMI<30) and from younger females with pathological obesity (n=3, mean age 34±2 years, mean BMI>40). First of all the immunophenotype of hASCs has been analyzed by FACS, and the expression of specific Mesenchymal Stem Cells markers was detected: CD34 and CD49d antigens are differently expressed in cells derived from younger and elder women, whereas the expression of CD29, CD34, CD90 and CD166 markers is modified in hASCs isolated from healthy and obese females. Next we have evaluated a different ability of hASCs to produce colonies and to osteo-differentiate. We have observed that the number of cells derived from younger women is significantly more abundant (p<0.005) respect to elder women together with a higher clonogenic potential (p<0.007); in contrast, hASCs derived from obese donors show a similar clonogenic potential and a faster proliferation rate. Osteogenic potential of hASCs derived from younger women appears more pronounced compared to cells derived from elder and obese ones. Our study indicates that the immune-phenotype, the self-renewal and the osteogenic potential of hASCs may be affected by both physiological and pathological conditions suggesting that not all the hASC’s sources may be ideal for future clinical applications.