The combined mechanism of bone morphogenetic protein- and calcium phosphate-induced skeletal tissue formation by human periosteum derived cells

Abstract

When combining osteogenic progenitor cells such as human periosteum derived cells (hPDCs) with osteoconductive biomaterials like calcium phosphate (CaP)-scaffolds, in vivo bone formation can be achieved. This process is dependent on the early activation of Bone morphogenetic protein (BMP)-signalling. However, the bone forming process is slow and routinely only a limited amount of bone and bone marrow is formed. Therefore, we hypothesised that a robust clinically relevant outcome could be achieved by adding more physiological levels of potent BMP-ligands to these cell-and CaP-based constructs.For this, hPDCs were characterised for their responsiveness to BMP-ligands upon in vitro 2D stimulation. BMP-2, -4, -6 and -9 robustly induced osteochondrogenic differentiation. Subsequently, these ligands were coated onto clinically approved CaP-scaffolds, BioOss ® and CopiOs ® , followed by hPDC-seeding. Protein lysates and conditioned media were investigated for activation of BMP signalling pathways. Upon in vivo implantation, the most abundant bone formation was found in BMP-2 and BMP-6-coated scaffolds. Implanted cells actively contributed to the newly formed bone. Remnants of cartilage could be observed in BMP-coated CopiOs ® -constructs.Computational analysis displayed that the type of BMPligand as well as the CaP-scaffold affects skeletal tissue formation, observed in a qualitative as well as quantitative manner. Furthermore, the in vitro mechanism appears to predict the in vivo outcome. This study presents further evidence for the potential of BMP-technology in the development of clinically relevant cell-based constructs for bone regenerative strategies.

RGD‐functionalized polyethylene glycol hydrogels support proliferation and in vitro chondrogenesis of human periosteum‐derived cells

“…CDM‐BMP2 was developed from selected components that, when combined, were able to re‐express the cartilage phenotype and maintain chondrocytes under serum free conditions . Additionally, this medium supplemented with BMP‐2 displayed promising initial results for the chondrogenic differentiation of hPDCs within our labs . The 4C medium, composed of TGF‐β1, ascorbic acid, dexamethasone, and ITS+, was optimized for ATDC‐5 cells, a chondrogenic cell line derived from murine teratocarcinoma.…”

“…The chondrogenic priming of MSC‐laden constructs seems to provide a suitable environment for in vitro chondrogenic differentiation . hPDCs also display a favorable outcome when stimulated with these growth factors, either in a micromass culture system or seeded on a 3D scaffold . However, these cells have not been tested within hydrogels, and we believe encapsulation of hPDCs within a hydrogel is an alternative in vitro culture approach worth investigating.…”

Reduction of BMP6‐induced bone formation by calcium phosphate in wild‐type compared with nude mice

“…These data suggest that different final local concentrations of free Ca 2+ might be, at least partially, responsible for the different bone‐forming capacity of CopiOs and CaCl 2 gels. Indeed, CopiOs displays an extremely fast release of CaP (Kerckhofs et al, ), leading to a burst of Ca 2+ that triggers the inhibition of Wnt‐signalling through elevated PKC phosphorylation in hPDCs, which is potentially the main factor contributing to the abrogation of bone formation (Bolander, Ji, et al, ). In parallel, other factors may also play an important role in the ectopic bone formation process, including granules size and biodegradability.…”

“…Two CaP‐based scaffolds were selected based on their bone‐forming capacity when combined with BMPs: BioOss® (Geistlich, Princeton, U.S.) and Copios® (Zimmer, Wemmel, BE; Bolander et al, ; Roberts et al, ). Small cylindrical samples of approximately 3‐mm diameter and 3–5‐mm height were punched out of the original CopiOs or BioOss sponges by using a metal punch and loaded with the 40, 120, or 240 ng/mm 3 rBMP6 (PeproTech) for 1 hr at 37°C, as previously described (Eyckmans, Roberts, Schrooten, & Luyten, ).…”

Single-cell characterization and metabolic profiling of in vitro cultured human skeletal progenitors with enhanced in vivo bone forming capacity

“…Similarly to in vivo fracture healing in mice, in vitro expanded hPDCs delivered on a ceramic scaffold require active bone morphogenetic protein (BMP)‐signaling during ectopic in vivo bone formation . Notably, exogenous BMP‐stimulation could further enhance the bone forming capacity . Moreover, it was reported that the osteochondrogenic potential of in vitro expanded hPDCs could be associated with elevated mRNA transcripts of the BMP type 1 and type 2 receptors .…”