psf c in control medium on plga large fiber scaffolds glf c in control medium on plga small fiber scaffolds gsf c in osteogenic inducing medium on plla large fiber scaffolds plf os in osteogenic inducing medium on plla small fiber scaffolds psf os in osteogenic inducing medium on plga large fiber scaffolds glf os and in osteogenic inducing medium on plga small fiber scaffolds gsf os fig5 and 6 show that calcium levels for cells grown on plla and plga large and small fiber scaffolds in os media are significantly higher on day 11 than on day 7 this shows positive differentiation in os medium and that all of the scaffolds can support differentiation successfully no differences attributable to either fiber size or polymer composition were observed as shown in fig7 sems of cells growing on a gsf and b psf scaffolds in os medium for 14 days show a uniform distribution of cells throughout all the scaffolds and an abundant mineralization of the extracellular matrix cells form a uniform cell layer embedded in extracellular matrix across the surface and interior of the scaffolds plla and plga were made into 1 mm thick non woven mats of two distinctly different fiber diameters nanometer sf and micrometer lf by electrospinning as described in example 1 and were sterilized prior to cell seeding sem mercury intrusion porosimetry mip and differential scanning calorimetry dsc were used to determine fiber diameter and cell morphology porosity and pore size distribution and thermal profile respectively to determine the chondrogenic potential of mscs on lf and sf mscs isolated from whole bone marrow and subcultured as described in example 1 were seeded onto lf and sf scaffolds at a density of 1 u00d7 10 5 cells cm 2 cells were maintained in chondrogenic induction.