Analysis of the osteoinductive capacity and angiogenicity of an in vitro generated extracellular matrix

Abstract

In this study, the osteoinductive potential of an in vitro generated extracellular matrix (ECM) deposited by marrow stromal cells seeded onto titanium fiber mesh scaffolds and cultured in a flow perfusion bioreactor was investigated. Culture periods of 8, 12, and 16 days were selected to allow for different amounts of ECM deposition by the cells as well as ECM with varying degrees of maturity (Ti/ECM/d8, Ti/ECM/d12, and Ti/ECM/d16, respectively). These ECM-containing constructs were implanted intramuscularly in a rat animal model. After 56 days, histologic analysis of retrieved constructs revealed no bone formation in any of the implants. Surrounding many of the implants was a fibrous capsule, which was often interspersed with fat cells. Within the pore spaces, the predominant tissue response was the presence of blood vessels and young fibroblasts or fat cells. The number of blood vessels on a per area basis calculated from a histomorphometric analysis increased as a function of the amount of ECM within the implanted constructs, with a significant difference between Ti/ECM/d16 and plain Ti constructs. These results indicate that although an in vitro generated ECM alone may not induce bone formation at an ectopic site, its use may enhance the vascularization of implanted constructs.

Cell-Derived Matrix Enhances Osteogenic Properties of Hydroxyapatite

“…The previous study reports have indicated that in vitro-generated ECM had an impact on the osteoblastic differentiation of mesenchymal stem cells in vitro, and in vivo. 9,10,19,20 In the present study it has been hypothesized that HA modified by the ECM secreted by the primary cells possesses necessary stimuli to enhance bone tissue repair, and provides a three-dimensional environment for the host progenitor The basic approach used in this study was to allow cells to deposit their own ECM followed by removal of the cells while preserving the native constituents and topography of the generated matrix. The primary cells required culture at high density with the media supplemented with high l-AA concentration to produce 3D ECM matrices.…”

“…10 Briefly, at the end of the culture period all constructs were rinsed in DPBS, and either frozen in LN 2 for 10 min, undergoing freeze-thaw cycle three …”

“…8 ECM secreted by cells on titanium scaffold in vitro effectively directed gene expression of bone marrow stromal cells. 9,10 However, to our knowledge, there have been no studies aiming to generate ECM in vitro as means to increase the osteogenic properties of the HA scaffold. Thus, realizing the significance of the ECM for the progenitor cell differentiation and bone regeneration, we have aimed (1) to design a HA-ECM composite scaffold by exploiting the natural ability of the primary cells to secrete ECM proteins and growth factors in vitro, and (2) to test the osteogenic properties of the generated HA-ECM construct in vivo.…”

Engineered decellularized matrices to instruct bone regeneration processes

“…Such eECM were also demonstrated to support the in vitro expansion of late-passaged human MSC, and also to dramatically improve their osteogenic capacity [72,73]. In vivo, eECM displayed efficient engraftment [74] and vascularization [75] and was capable to undergo remodeling onto an immature osteoid tissue [71]. eECM was successfully shown to act as functional/instructive template for the regulation and/or recruitment of osteoprogenitor cells, although it could not ectopically induce frank bone formation in mouse and rat models [71,76].…”

Role of Mesenchymal Stem Cells in Bone Regenerative Medicine: What Is the Evidence?

“…Recently, investigations have focused on designing new vehicles by using the decellularized matrices (natural ECM). Numerous studies have shown the promising osteogenic effects of MSC-laden decellularized ECMs in the absence of osteogenic cell culture supplements or any growth factors [Datta et al, 2006;Pham et al, 2009;Liao et al, 2010]. One study showed that MSCs seeded with ECM construct and cultured in medium either with or without dexamethasone revealed similar amounts of calcium deposition after 16 days.…”