Differential effects of hypoxia on osteochondrogenic potential of human adipose-derived stem cells

Abstract

Guicheux J. Differential effects of hypoxia on osteochondrogenic potential of human adipose-derived stem cells. Am J Physiol Cell Physiol 298: C355-C364, 2010. First published November 25, 2009 doi:10.1152/ajpcell.00398.2009.-Human adipose tissue-derived stem cells (hATSC) have been contemplated as reparative cells for cartilage engineering. Chondrogenic differentiation of hATSC can be induced by an enriched culture medium and a three-dimensional environment. Given that bone is vascularized and cartilage is not, oxygen tension has been suggested as a regulatory factor for osteochondrogenic differentiation. Our work aimed at determining whether hypoxia affects the osteochondrogenic potential of hATSC. hATSC were cultured in chondrogenic or osteogenic medium for 28 days, in pellets or monolayers, and under 5% or 20% oxygen tension. Cell differentiation was monitored by real-time PCR (COL2A1, aggrecan, Runx2, and osteocalcin). The chondrogenic differentiation was further evaluated by Alcian blue and immunohistological staining for glycosaminoglycans (GAGs) and type II collagen, respectively. Osteogenic differentiation was also assessed by the staining of mineralized matrix (Alizarin Red) and measurement of alkaline phosphatase (ALP) activity. The expression of chondrogenic markers was upregulated when hATSC were exposed to hypoxia in chondrogenic medium. Conversely, osteocalcin expression, mineralization, and ALP activity were severely reduced under hypoxic conditions even in the presence of osteogenic medium. Our data strongly suggest that hypoxia favors the chondrogenic differentiation of hATSC as evidenced by the expression of the chondrogenic markers, whereas it could alter their osteogenic potential. Our results highlight the differential regulatory role of hypoxia on the chondrogenic and osteogenic differentiation processes of hATSC. These data could help us exploit the potential of tissue engineering and stem cells to replace or restore the function of osteoarticular tissues.

Cell-specific effects of TNF-α and IL-1β on alkaline phosphatase: implication for syndesmophyte formation and vascular calcification

“…Pellets were cultured for 21 days in FCS-free DMEM supplemented with 10 mg/ml of bovine insulin, 50 mM of ascorbic acid, 10 À8 M of dexamethasone and 10 ng/ml of TGF-b1, as detailed elsewhere. 27 To induce calcification, pellets were then cultured in a-MEM containing 5% FCS, 10 mg/ml of insulin, 10 À8 M 1,25 (OH) 2 VD 3 and 5 mM b-GP. Pellets were finally treated on day 24 with 1 ng/ml of TNF-a and 0.1 ng/ml of IL-1b for 2 days for PCR analysis or 7 days to assess TNAP activity.…”

Role of Articular Disc in Condylar Regeneration of the Mandible

“…They also reported that autologous pericranial graft resurfacing was performed after condylectomy and discectomy, and showed regenerated condyle with hyaline cartilage; they concluded that pericranial grafts controlled oxygen tension in the TMj. relatively low oxygen tension favors differentiation into cartilage cells, which occurs on the articular surface [10]. Fujita et al [6] reported that mesenchymal cell aggregation in the resection area was confirmed in the early stage of condylar regeneration.…”

Tissue Engineering for Tissue and Organ Regeneration

“…Low oxygen levels have been reported to be a more potent promoter of chondrogenesis than dynamic compression (Meyer et al, 2010). Previous studies have shown controversial findings in relation to the effect of oxygen tension on chondrogenic differentiation of mesenchymal stem cells with some reporting increased proliferation rates and chondrogenic potency and others reporting reduced proliferation and differentiation potency (Grayson et al, 2007;Merceron et al, 2010;Krinner et al, 2009;Holzwarth et al, 2010). …”