Stimulation of a calcified cartilage connecting zone by GDF‐5‐augmented fibrin hydrogel in a novel layered ectopic in vivo model

Abstract

Tissue engineering approaches for reconstructing full-depth cartilage defects need to comprise a zone of calcified cartilage to tightly anchor cartilage constructs into the subchondral bone. Here, we investigated whether growth and differentiation factor-5-(GDF-5)-augmented fibrin hydrogel can induce a calcified cartilage-layer in vitro that seamlessly connects cartilage-relevant biomaterials with bone tissue. Human bone marrow stromal cells (BMSCs) were embedded in fibrin hydrogel and subjected to chondrogenesis with TGF-β with or without GDF-5 before constructs were implanted subcutaneously into SCID mice. A novel layered ectopic in vivo model was developed and GDF-5-augmented fibrin with BMSCs was used to glue hydrogel and collagen constructs onto bone disks to investigate formation of a calcified cartilage connecting zone. GDF-5 significantly enhanced ALP activity during in vitro chondrogenesis while ACAN and COL2A1 mRNA, proteoglycan-, collagen-type-II- and collagen-type-X-deposition remained similar to controls. Pellets pretreated with GDF-5 mineralized faster in vivo and formed more ectopic bone. In the novel layered ectopic model, GDF-5 strongly supported calcified cartilage formation that seamlessly connected with the bone. Pro-chondrogenic and pro-hypertrophic activity makes GDF-5-augmented fibrin an attractive bioactive hydrogel with high potential to stimulate a calcified cartilage connecting zone in situ that might promote integration of cartilage scaffolds with bone. Thus, GDF-5-augmented fibrin hydrogel promises to overcome poor fixation of biomaterials in cartilage defects facilitating their long-term regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2214-2224, 2018.

Significance of MEF2C and RUNX3 Regulation for Endochondral Differentiation of Human Mesenchymal Progenitor Cells

“…Strong staining of SAOS-2 cells embedded in fibrin hydrogel to allow identical processing, confirmed a positive MEF2C, RUNX3, and RUNX2 staining (Supplementary Figure S2C). This underlined the main findings of Western blots and demonstrated that mainly peripheral MPCs underwent hypertrophy, which is in line with peripheral detection of ALP activity (Supplementary Figure S2A) reported before (Dickhut et al, 2009;Fischer et al, 2010;Mueller et al, 2013;Diederichs et al, 2017). In conclusion, specific microenvironmental conditions like higher oxygen and/or better FIGURE 2 | Characterization of MPC and AC differentiation.…”

Decellularized Articular Cartilage Microgels as Microcarriers for Expansion of Mesenchymal Stem Cells

“…The hMSCs encapsulated in the alginate gel without CMGs was used as the control group. The mRNA expressions included Sox-9 [ 23 ], SZP as the superficial zone marker [ 25 ], Col II, and AGC as the middle zone markers [ 26 ], and Col X and ALP as markers of cartilage hypertrophy in the calcified zone of articular cartilage [ 27 ]. For all markers and culture times, the expressions for aCMG-MSCs and fCMG-MSCs were higher than the control group.…”

Decellularized Articular Cartilage Microparticles for Expansion of Mesenchymal Stem Cells and Zonal Regeneration of Articular Cartilage

“…The control group in exhibit A was MSCs encapsulated directly, without CMPs, in alginate. Chondrogenic markers included Sox-9 [37], SZP as the superficial zone marker [39], Col II and AGC as the middle zone markers [16], and Col X and ALP as calcified zone markers [40]. For all markers and incubation times, adult or fetal CMP-MSCs showed higher expressions compared to directly encapsulated MSCs in alginate.…”