BMP9 is a potent inducer of chondrogenesis, volumetric expansion and collagen type II accumulation in bovine auricular cartilage chondroprogenitors.

Reconstruction of the outer ear currently requires harvesting of cartilage from the posterior of the auricle or ribs leading to pain and donor site morbidity. An alternative source for auricular reconstruction is in vitro tissue engineered cartilage using stem/progenitor cells. Several candidate cell-types have been studied with tissue-specific auricular cartilage progenitor cells (AuCPC) of particular interest.

Human platelet lysate enhances proliferation but not chondrogenic differentiation of pediatric mesenchymal progenitors.

Background Aims: Cell therapies have the potential to improve reconstructive procedures for congenital craniofacial cartilage anomalies such as microtia. Adipose-derived stem cells (ADSCs) and auricular cartilage stem/progenitor cells (CSPCs) are promising candidates for cartilage reconstruction, but their successful use in the clinic will require the development of xeno-free expansion and differentiation protocols that can maximize their capacity for chondrogenesis.

Methods: We assessed the behavior of human ADSCs and CSPCs grown either in qualified fetal bovine serum (FBS) or human platelet lysate (hPL), a xeno-free alternative, in conventional monolayer and 3-dimensional spheroid cultures.

Three-dimensional environment and vascularization induce osteogenic maturation of human adipose-derived stem cells comparable to that of bone-derived progenitors.

While human adipose-derived stem cells (hADSCs) are known to possess osteogenic differentiation potential, the bone tissues formed are generally considered rudimentary and immature compared with those made by bone-derived precursor cells such as human bone marrow-derived mesenchymal stem cells (hBMSCs) and less commonly studied human calvarium osteoprogenitor cells (hOPs). Traditional differentiation protocols have tended to focus on osteoinduction of hADSCs through the addition of osteogenic differentiation media or use of stimulatory bioactive scaffolds which have not resulted in mature bone formation. Here, we tested the hypothesis that by reproducing the physical as well as biochemical bone microenvironment through the use of three-dimensional (3D) culture and vascularization we could enhance osteogenic maturation in hADSCs.

Bone Morphogenetic Protein-9 Is a Potent Chondrogenic and Morphogenic Factor for Articular Cartilage Chondroprogenitors.

Articular cartilage contains a subpopulation of tissue-specific progenitors that are an ideal cell type for cell therapies and generating neocartilage for tissue engineering applications. However, it is unclear whether the standard chondrogenic medium using transforming growth factor beta (TGFβ) isoforms is optimal to differentiate these cells. We therefore used pellet culture to screen progenitors from immature bovine articular cartilage with a number of chondrogenic factors and discovered that bone morphogenetic protein-9 (BMP9) precociously induces their differentiation.

Improved Chondrogenic Differentiation of rAAV SOX9-Modified Human MSCs Seeded in Fibrin-Polyurethane Scaffolds in a Hydrodynamic Environment.

The repair of focal articular cartilage defects remains a problem. Combining gene therapy with tissue engineering approaches using bone marrow-derived mesenchymal stem cells (MSCs) may allow the development of improved options for cartilage repair. Here, we examined whether a three-dimensional fibrin-polyurethane scaffold provides a favorable environment for the effective chondrogenic differentiation of human MSCs (hMSCs) overexpressing the cartilage-specific SOX9 transcription factor via recombinant adeno-associated virus (rAAV) -mediated gene transfer cultured in a hydrodynamic environment .

Parathyroid Hormone-Related Protein Gradients Affect the Progression of Mesenchymal Stem Cell Chondrogenesis and Hypertrophy.

Introduction: Mesenchymal stem cells (MSCs) are considered a promising cell source for cartilage repair strategies due to their chondrogenic differentiation potential. However, their in vitro tendency to progress toward hypertrophy limits their clinical use. This unfavorable result may be due to the fact that MSCs used in tissue engineering approaches are all at the same developmental stage, and have lost crucial spatial and temporal signaling cues.

Joint mimicking mechanical load activates TGFβ1 in fibrin-poly(ester-urethane) scaffolds seeded with mesenchymal stem cells.

Transforming growth factor-β1 (TGF-β1) is widely used in an active recombinant form to stimulate the chondrogenic differentiation of mesenchymal stem cells (MSCs). Recently, it has been shown that the application of multiaxial load, that mimics the loading within diarthrodial joints, to MSCs seeded in to fibrin-poly(ester-urethane) scaffolds leads to the endogenous production and secretion of TGF-β1 by the mechanically stimulated cells, which in turn drives the chondrogenic differentiation of the cells within the scaffold. The work presented in this short communication provides further evidence that the application of joint mimicking multiaxial load induces the secretion of TGF-β1 by mechanically stimulated MSCs.

Asymmetrical seeding of MSCs into fibrin-poly(ester-urethane) scaffolds and its effect on mechanically induced chondrogenesis.

Mesenchymal stem cells (MSCs) are currently being investigated as candidate cells for regenerative medicine approaches for the repair of damaged articular cartilage. For these cells to be used clinically, it is important to understand how they will react to the complex loading environment of a joint in vivo. In addition to investigating alternative cell sources, it is also important for the structure of tissue-engineered constructs and the organization of cells within them to be developed and, if possible, improved.

Mesenchymal Stem Cells Derived from Human Bone Marrow.

Mesenchymal stem cells are found in a number of tissues and have the potential to differentiate into a range of mesenchymal lineages. This ready availability and multipotent character means that mesenchymal stem cells have become a focus for the field of tissue engineering, particularly for the repair of bone and cartilage. This chapter describes the isolation of mesenchymal stem cells from human bone marrow tissue, as well as expansion of the cells and characterisation of their multipotency.

Induction of Osteogenic Differentiation in Human Mesenchymal Stem Cells by Crosstalk with Osteoblasts.

Natural bone healing following fractures is initiated by osteoblasts (OBs) and mesenchymal stem cells (MSCs), a cell combination with possible potential in tissue engineering techniques for bony defects. The aim of the study was to investigate MSC/OB-crosstalk, in order to determine optimal cell culture conditions for osteogenic differentiation. Human OBs and MSCs interactions were investigated in an in vitro trans-well co-culture study over a time period of 28 days.

Human Articular Cartilage Progenitor Cells Are Responsive to Mechanical Stimulation and Adenoviral-Mediated Overexpression of Bone-Morphogenetic Protein 2.

Articular cartilage progenitor cells (ACPCs) represent a new and potentially powerful alternative cell source to commonly used cell sources for cartilage repair, such as chondrocytes and bone-marrow derived mesenchymal stem cells (MSCs). This is particularly due to the apparent resistance of ACPCs to hypertrophy. The current study opted to investigate whether human ACPCs (hACPCs) are responsive towards mechanical stimulation and/or adenoviral-mediated overexpression of bone morphogenetic protein 2 (BMP-2).