Adipose stem cells can secrete angiogenic factors that inhibit hyaline cartilage regeneration

Abstract

IntroductionAdipose stem cells (ASCs) secrete many trophic factors that can stimulate tissue repair, including angiogenic factors, but little is known about how ASCs and their secreted factors influence cartilage regeneration. Therefore, the aim of this study was to determine the effects ASC-secreted factors have in repairing chondral defects.MethodsASCs isolated from male Sprague Dawley rats were cultured in monolayer or alginate microbeads supplemented with growth (GM) or chondrogenic medium (CM). Subsequent co-culture, conditioned media, and in vivo cartilage defect studies were performed.ResultsASC monolayers and microbeads cultured in CM had decreased FGF-2 gene expression and VEGF-A secretion compared to ASCs cultured in GM. Chondrocytes co-cultured with GM-cultured ASCs for 7 days had decreased mRNAs for col2, comp, and runx2. Chondrocytes treated for 12 or 24 hours with conditioned medium from GM-cultured ASCs had reduced sox9, acan, and col2 mRNAs; reduced proliferation and proteoglycan synthesis; and increased apoptosis. ASC-conditioned medium also increased endothelial cell tube lengthening whereas conditioned medium from CM-cultured ASCs had no effect. Treating ASCs with CM reduced or abolished these deleterious effects while adding a neutralizing antibody for VEGF-A eliminated ASC-conditioned medium induced chondrocyte apoptosis and restored proteoglycan synthesis. FGF-2 also mitigated the deleterious effects VEGF-A had on chondrocyte apoptosis and phenotype. When GM-grown ASC pellets were implanted in 1 mm non-critical hyaline cartilage defects in vivo, cartilage regeneration was inhibited as evaluated by radiographic and equilibrium partitioning of an ionic contrast agent via microCT imaging. Histology revealed that defects with GM-cultured ASCs had no tissue ingrowth from the edges of the defect whereas empty defects and defects with CM-grown ASCs had similar amounts of neocartilage formation.ConclusionsASCs must be treated to reduce the secretion of VEGF-A and other factors that inhibit cartilage regeneration, which can significantly influence how ASCs are used for repairing hyaline cartilage.

A three-dimensional dynamic coculture system enabling facile cell separation for chondrogenesis of mesenchymal stem cells

“…In fact, it has been implicated that the apparent effects of coculture can be dependent on a variety of factors, including medium component (i.e., FBS and TGF-␤), the nature of biomaterial matrix (e.g., alginate versus collagen) and cell ratio [39]. In several studies, varying effects of coculture in chondrocyte growth medium and chondrogenic medium has been observed, suggesting that FBS may modulate the coculture between MSCs and ACs [27,40]. Additionally, addition of FBS was able to attenuate death of rMSCs in this chondrogenic induction condition (data not shown) [37].…”

Therapeutic application of mesenchymal stem cells in osteoarthritis

“…Using in vitro chondrocyte coculture models, a number of studies reported that MSCs promote chondrocyte proliferation and stimulate ECM synthesis [65][66][67]. Other reports described the inhibitory effect of MSCs on chondrocyte differentiation [68,69]. In our group, we showed that coculture of both BM-MSCs and ASCs with primary chondrocytes isolated from OA patients did not influence the expression of cartilage markers, such as Sox9 or Aggrecan but significantly reduced the expression of fibrotic and hypertrophic markers, which are expressed by OA cartilage [70].…”

Dual functional nanoparticles containing SOX duo and ANGPT4 shRNA for osteoarthritis treatment

“…4 Adipose-derived stem cells (ADSCs) may serve as a better source for regenerative medicine due to their availability and ease of procurement, 5 although their use for cartilage regeneration appears challenging as they have lower chondrogenic potential than BMSCs, 6 release of angiogenic factors such as vascular endothelial growth factor (VEGF)-A that inhibit cartilage regeneration. 7 However, preconditioning ADSCs with activated platelet-rich plasma (PRP) or their genetic engineering with sex-determining region SRY (SOX)-trio (SOX5, 6 and 9) genes enhances chondrogenic potential. [8][9][10][11] SOX-trio (SOX-5, -6 and -9) are transcription factors that belong to the same family of regulatory molecules.…”