title: Enhanced MSC chondrogenesis following delivery of TGF-β3 from alginate microspheres within hyaluronic acid hydrogels in vitro and in vivo.
abstract: Mesenchymal stem cells (MSCs) are being recognized as a viable cell source for cartilage repair and members of the transforming growth factor-beta (TGF-β) superfamily are a key mediator of MSC chondrogenesis. While TGF-β mediated MSC chondrogenesis is well established in in vitro pellet or hydrogel cultures, clinical translation will require effective delivery of TGF-βs in vivo. Here, we investigated the co-encapsulation of TGF-β3 containing alginate microspheres with human MSCs in hyaluronic acid (HA) hydrogels towards the development of implantable constructs for cartilage repair. TGF-β3 encapsulated in alginate microspheres with nanofilm coatings showed significantly reduced initial burst release compared to uncoated microspheres, with release times extending up to 6 days. HA hydrogel constructs seeded with MSCs and TGF-β3 containing microspheres developed comparable mechanical properties and cartilage matrix content compared to constructs supplemented with TGF-β3 continuously in culture media, whereas constructs with TGF-β3 directly encapsulated in the gels without microspheres had inferior properties. When implanted subcutaneously in nude mice, constructs containing TGF-β3 microspheres resulted in superior cartilage matrix formation when compared to groups without TGF-β3 or with TGF-β3 added directly to the gel. However, calcification was observed in implanted constructs after 8 weeks of subcutaneous implantation. To prevent this, the co-delivery of parathyroid hormone-related protein (PTHrP) with TGF-β3 in alginate microspheres was pursued, resulting in partially reduced calcification. This study demonstrates that the controlled local delivery of TGF-β3 is essential to neocartilage formation by MSCs and that further optimization is needed to avert the differentiation of chondrogenically induced MSCs towards a hypertrophic phenotype.
authors.affiliation: Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 South 33rd Street, Philadelphia, PA 19104, United States.
authors.forename: Liming
authors.initials: L
authors.lastname: Bian
authors.forename: David Y
authors.initials: DY
authors.lastname: Zhai
authors.forename: Elena
authors.initials: E
authors.lastname: Tous
authors.forename: Reena
authors.initials: R
authors.lastname: Rai
authors.forename: Robert L
authors.initials: RL
authors.lastname: Mauck
authors.forename: Jason A
authors.initials: JA
authors.lastname: Burdick
mesh_terms: D000464:Alginates / Q000737:chemistry*; D000818:Animals; D002356:Cartilage / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D020219:Chondrogenesis / Q000187:drug effects*; D055119:Elastic Modulus / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006801:Humans; D006820:Hyaluronic Acid / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D007150:Immunohistochemistry; D020007:Implants, Experimental; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008863:Microspheres; D044162:Parathyroid Hormone-Related Protein / Q000494:pharmacology; D053782:Transforming Growth Factor beta3 / Q000494:pharmacology*
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D020100:Hydrogels; D044162:Parathyroid Hormone-Related Protein; D053782:Transforming Growth Factor beta3; D020723:Glucuronic Acid; D006820:Hyaluronic Acid