[1] Univ Pittsburgh, Sch Med, Childrens Hosp Pittsburgh, Stem Cell Res Ctr, Pittsburgh, PA 15213 USA
[2] Univ Pittsburgh, Med Ctr, Dept Orthopaed Surg, Pittsburgh, PA 15213 USA
[3] Dept Microbiol & Mol Genet, Pittsburgh, PA 15261 USA
[4] Univ Pittsburgh, Dept Bioengn, Pittsburgh, PA 15261 USA
[5] Univ Pittsburgh, Med Ctr, Dept Orthopaed Surg, Pittsburgh, PA 15203 USA