Chondrogenic differentiation of mouse CD105+ stem/progenitor cells on amino-group-functionalized biosilica-hydrogel scaffolds

Objectives: Mesenchymal stem/progenitor cells (MSPCs) are critical for tissue regeneration. Moreover, the CD105 antigen identifies early MSPCs with increased chondrogenic differentiation ability. We hypothesized that amine-(NH₂)-functionalized biosilica incorporating hydrogel scaffolds, seeded with mCoSPCs¹⁰⁵⁺ would contribute to creating tissue-engineered scaffolds, capable of de novo cartilage synthesis. Materials and Methods: Scaffolds were characterized by water uptake, lysozyme degradation, axial compression, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Differentiation stimulus of scaffold functionalization was evaluated using Alcian blue staining. Cartilage-forming abilities of mCoSPCs¹⁰⁵⁺ were evaluated using Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunohistochemistry. Results: Biosilica particle incorporation into scaffolds resulted in increased water uptake capacity and compression force withstanding abilities. Amine-(NH₂)-group functionalization of biosilica led to significantly increased stem cell differentiation potential, by Alcian blue staining, in the first 3 weeks. Scaffold attachment and viable cell proliferation were observed for 6 weeks under chondrogenic differentiation. Downregulation of Runx2, an increase of Col10a1, Ihh, and maintenance of Sox9, was seen under these culture conditions. mCoSPCs¹⁰⁵⁺ gene expression pattern was defined by the significant upregulation of Col1a1, Col2a1, Prg4, and Agc-1 over 6 weeks of incubation compared to the unsorted control. Immunostaining of cell-seeded scaffolds revealed significantly higher secretion of proteins relevant to cartilage extracellular matrix. Conclusion: The preselecting of CD105⁺ phenotype in MSPCs may enhance tissue regeneration of fibrocartilage and biosilica nanoparticles may be a beneficial additive in tissue engineering of scaffolds.