Changes of chondrocyte expression profiles in human MSC aggregates in the presence of PEG microspheres and TGF-β3

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-μs). 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-μs. An outer fibrous layer always found in differentiated MSC aggregate cultures was not formed in the presence of PEG-μs. 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-μs aggregates. Ubiquitous deposition of type I and type X collagen proteins was found in MSC/PEG-μs 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-μs 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-μs cultures, the surprisingly large impact of the microparticles themselves should be considered when designing drug delivery/scaffold strategies.

Silk fibroin/cartilage extracellular matrix scaffolds with sequential delivery of TGF-β3 for chondrogenic differentiation of adipose-derived stem cells

“…21,22 To regulate the release of factors, loading microparticle containing factors into the scaffolds 23 and covalently binding the factors to the scaffolds have been used in recent research of chondrogenesis. 24,25 However, the effect of microspheres themselves on cell differentiation and covalent binding on the activity of factors cannot be well controlled, so both methods do not mimic the natural presentation of the factors in vitro. 26 In addition, the preparation of these controlled release systems is relatively complicated.…”

Chondroitin Sulfate Microparticles Modulate Transforming Growth Factor-β1-Induced Chondrogenesis of Human Mesenchymal Stem Cell Spheroids

“…To further enhance chondrogenesis and address issues of phenotype inhomogeneity, MPs have been cultured within MSC pellets in order to introduce differentiation cues in a more uniform manner [Fan et al, 2008; Solorio et al, 2010; Ravindran et al, 2011; Ansboro et al, 2014]. Prior experiments have investigated the effects of poly(lactic-co-glycolic acid) (PLGA), poly(ethylene glycol) (PEG), hyaluronic acid (HA) MPs, or gelatin MPs on chondrogenesis of MSC pellets [Fan et al, 2008; Solorio et al, 2010; Ravindran et al, 2011; Ansboro et al, 2014].…”

“…Prior experiments have investigated the effects of poly(lactic-co-glycolic acid) (PLGA), poly(ethylene glycol) (PEG), hyaluronic acid (HA) MPs, or gelatin MPs on chondrogenesis of MSC pellets [Fan et al, 2008; Solorio et al, 2010; Ravindran et al, 2011; Ansboro et al, 2014]. The incorporation of gelatin [Fan et al, 2008] and PEG MPs [Ravindran et al, 2011] induced GAG and collagen II production comparable to pellets lacking MPs, while PLGA MPs promoted more homogeneous GAG deposition [Solorio et al, 2010]. In addition, PEG MPs reduced collagen I and X gene expression, which are markers of non-articular chondrocyte phenotypes.…”

“…While a variety of biomaterials may be used in fabrication of MPs for enhanced chondrogenesis [Fan et al, 2008; Solorio et al, 2010; Ravindran et al, 2011; Ansboro et al, 2014], GAGs such as chondroitin sulfate (CS) are of particular interest since they are found in cartilaginous condensations during embryonic development and CS is a major component of mature articular cartilage [DeLise et al, 2000]. CS is negatively charged due to the presence of sulfate groups on the disaccharide units and, thus, it can bind positively-charged growth factors electrostatically and provide compressive strength to cartilage through ionic interactions with water [Poole et al, 2001].…”

Mechanical Loading Promoted Discogenic Differentiation of Human Mesenchymal Stem Cells Incorporated in 3D-PEG Scaffolds with rhGDF5 and RGD

“…It has been speculated that hMSC can thrive especially well in the undifferentiated state in presence of RGD [10]. Recently, it has been investigated whether hMSCs can be pushed towards the discogenic pathway by the addition of RGD motive [13,14]. The recent study found a weaker effect of transforming and growth factor β 3 (TGFβ 3 ) [10] if RGD motive was added to an alginate culture system.…”