Transforming growth factor-beta stimulates human bone marrow-derived mesenchymal stem/stromal cell chondrogenesis more so than kartogenin

E Music,M R Doran,T J Klein,W B Lott

doi:10.1038/s41598-020-65283-8

Abstract

A previous study identified kartogenin (KGN) as a potent modulator of bone marrow mesenchymal stem/stromal cell (BMSC) chondrogenesis. This initial report did not contrast KGN directly against transforming growth factor-beta 1 (TGF-β1), the most common growth factor used in chondrogenic induction medium. Herein, we directly compared the in vitro chondrogenic potency of TGF-β1 and KGN using a high resolution micropellet model system. Micropellets were cultured for 7–14 days in medium supplemented with TGF-β1, KGN, or both TGF-β1 + KGN. Following 14 days of induction, micropellets exposed to TGF-β1 alone or TGF-β1 + KGN in combination were larger and produced more glycosominoglycan (GAG) than KGN-only cultures. When TGF-β1 + KGN was used, GAG quantities were similar or slightly greater than the TGF-β1-only cultures, depending on the BMSC donor. BMSC micropellet cultures supplemented with KGN alone contracted in size over the culture period and produced minimal GAG. Indicators of hypertrophy were not mitigated in TGF-β1 + KGN cultures, suggesting that KGN does not obstruct BMSC hypertrophy. KGN appears to have weak chondrogenic potency in human BMSC cultures relative to TGF-β1, does not obstruct hypertrophy, and may not be a viable alternative to growth factors in cartilage tissue engineering.

Highlights

A previous study identified kartogenin (KGN) as a potent modulator of bone marrow mesenchymal stem/stromal cell (BMSC) chondrogenesis
Over 14 days of culture, micropellets cultured in TGF-β1 and TGF-β1 + KGN increased in diameter, while KGN micropellets decreased in size (Fig. 2, Supplementary Figs. 1 and 2)
Glycosaminoglycan (GAG) production by the three BMSC donors differed in response to TGF-β1 and KGN, but there was a consistent pattern indicating that the presence of TGF-β1 was required to maximise micropellet GAG content

Summary

Introduction

A previous study identified kartogenin (KGN) as a potent modulator of bone marrow mesenchymal stem/stromal cell (BMSC) chondrogenesis This initial report did not contrast KGN directly against transforming growth factor-beta 1 (TGF-β1), the most common growth factor used in chondrogenic induction medium. KGN appears to have weak chondrogenic potency in human BMSC cultures relative to TGF-β1, does not obstruct hypertrophy, and may not be a viable alternative to growth factors in cartilage tissue engineering. Our team developed a microwell platform with the aim of being able to manufacture hundreds of smaller diameter pellets (micropellets, 5×103 cells each) that would yield more homogeneous cartilage-like tissue[8]. We used the Microwell-mesh to manufacture hundreds of small diameter cartilage micropellets (5×103 BMSC each) from human BMSC and evaluated the chondrogenic potency of TGF-β1 alone, KGN alone, and TGF-β1 + KGN. Chondrogenesis was evaluated based on relative matrix accumulation, histology and gene expression

Methods

Results

Conclusion