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Updated: May 30, 2026
Differentiating Chondrocytes from Peripheral Blood-derived Human Induced Pluripotent Stem Cells
Published on: July 18, 2017
Changes of chondrocyte expression profiles in human MSC aggregates in the presence of PEG microspheres and TGF-β3
Soumya Ravindran1, Jacob L Roam, Peter K Nguyen
1Department of Orthopaedic Surgery, Washington University School of Medicine, 660 South Euclid Avenue, St Louis, MO 63110, USA.
Abstract:
Biomaterial microparticles are commonly utilized as growth factor delivery vehicles to induce chondrogenic differentiation of mesenchymal stem/stromal cells (MSCs). To address whether the presence of microparticles could themselves affect differentiation of MSCs, a 3D co-aggregate system was developed containing an equal volume of human primary bone marrow-derived MSCs and non-degradable RGD-conjugated poly(ethylene glycol) microspheres (PEG-micros). Following TGF-β3 induction, differences in cell phenotype, gene expression and protein localization patterns were found when compared to MSC aggregate cultures devoid of PEG-micros. An outer fibrous layer always found in differentiated MSC aggregate cultures was not formed in the presence of PEG-micros. Type II collagen protein was synthesized by cells in both culture systems, although increased levels of the long (embryonic) procollagen isoforms were found in MSC/PEG-micros aggregates. Ubiquitous deposition of type I and type X collagen proteins was found in MSC/PEG-micros cultures while the expression patterns of these collagens was restricted to specific areas in MSC aggregates. These findings show that MSCs respond differently to TGF-β3 when in a PEG-micros environment due to effects of cell dilution, altered growth factor diffusion and/or cellular interactions with the microspheres. Although not all of the expression patterns pointed toward improved chondrogenic differentiation in the MSC/PEG-micros cultures, the surprisingly large impact of the microparticles themselves should be considered when designing drug delivery/scaffold strategies.
Insights
Biomaterial microparticles, like poly(ethylene glycol) microspheres (PEG-micros), can alter mesenchymal stem/stromal cell (MSC) differentiation. Their presence impacts cell phenotype and collagen expression, independent of growth factor delivery.
Area of Science:
- Biomaterials Science
- Stem Cell Biology
- Tissue Engineering
Background:
- Biomaterial microparticles are widely used to deliver growth factors for chondrogenic differentiation of mesenchymal stem/stromal cells (MSCs).
- The potential influence of the microparticles themselves on MSC differentiation has not been fully elucidated.
Purpose of the Study:
- To investigate whether non-degradable RGD-conjugated poly(ethylene glycol) microspheres (PEG-micros) affect the chondrogenic differentiation of human bone marrow-derived MSCs.
- To compare MSC differentiation in a 3D co-aggregate system with PEG-micros versus MSC aggregates alone.
Main Methods:
- Development of a 3D co-aggregate system combining human primary bone marrow-derived MSCs and PEG-micros.
- Induction of chondrogenesis using TGF-β3.
- Analysis of cell phenotype, gene expression, and protein localization, including collagen types I, II, and X.
Main Results:
- MSC aggregates with PEG-micros exhibited altered cell phenotype, gene expression, and protein localization compared to MSC aggregates without microspheres.
- The characteristic outer fibrous layer of differentiated MSC aggregates was absent in the presence of PEG-micros.
- While Type II collagen was synthesized in both systems, MSC/PEG-micros aggregates showed increased embryonic procollagen isoforms and ubiquitous deposition of Type I and X collagens, unlike the localized expression in MSC aggregates.
Conclusions:
- MSCs respond differently to TGF-β3 induction when co-aggregated with PEG-micros, due to factors like cell dilution, altered growth factor diffusion, and microsphere-cell interactions.
- The physical presence of microparticles significantly impacts MSC differentiation outcomes, a factor crucial for designing biomaterial-based drug delivery and scaffold strategies.
