Fabrication of anatomically-shaped cartilage constructs using decellularized cartilage-derived matrix scaffolds

Abstract

The native extracellular matrix of cartilage contains entrapped growth factors as well as tissue-specific epitopes for cell-matrix interactions, which make it a potentially attractive biomaterial for cartilage tissue engineering. A limitation to this approach is that the native cartilage extracellular matrix possesses a pore size of only a few nanometers, which inhibits cellular infiltration. Efforts to increase the pore size of cartilage-derived matrix (CDM) scaffolds dramatically attenuate their mechanical properties, which makes them susceptible to cell-mediated contraction. In previous studies, we have demonstrated that collagen crosslinking techniques are capable of preventing cell-mediated contraction in CDM disks. In the current study, we investigated the effects of CDM concentration and pore architecture on the ability of CDM scaffolds to resist cell-mediated contraction. Increasing CDM concentration significantly increased scaffold mechanical properties, which played an important role in preventing contraction, and only the highest CDM concentration (11% w/w) was able to retain the original scaffold dimensions. However, the increase in CDM concentration led to a concomitant decrease in porosity and pore size. Generating a temperature gradient during the freezing process resulted in unidirectional freezing, which aligned the formation of ice crystals during the freezing process and in turn produced aligned pores in CDM scaffolds. These aligned pores increased the pore size of CDM scaffolds at all CDM concentrations, and greatly facilitated infiltration by mesenchymal stem cells (MSCs). These methods were used to fabricate of anatomically-relevant CDM hemispheres. CDM hemispheres with aligned pores supported uniform MSC infiltration and matrix deposition. Furthermore, these CDM hemispheres retained their original architecture and did not contract, warp, curl, or splay throughout the entire 28-day culture period. These findings demonstrate that given the appropriate fabrication parameters, CDM scaffolds are capable of maintaining complex structures that support MSC chondrogenesis.

Enhanced nutrient transport improves the depth-dependent properties of tri-layered engineered cartilage constructs with zonal co-culture of chondrocytes and MSCs

“…These constructs hold promise for restoring native tissue structure and function, and may be beneficial in terms of zone-to-zone integration with adjacent host tissue and providing more appropriate strain transfer after implantation. Future work will investigate how individual cells within each layer communicate with one another and with adjacent layers, and will scale this technology to produce constructs of anatomic relevance for cartilage repair applications [27, 28, 51]. …”

“…This suggests that insufficient soluble factor transport compromises and/or limits cell function in engineered constructs, ultimately resulting in inhomogeneous matrix accumulation [20, 24]. This issue is critical when considering scaling up to repair thicker cartilage regions (e.g., the femoral condyle) [23, 26] or larger defect areas (e.g., partial or total joint resurfacing) [27, 28]. …”

3D printing for the design and fabrication of polymer-based gradient scaffolds

“…Many studies begin with an overall scan of such scaffolds using micro computed tomography (µCT), allowing for visualization of bulk scaffold shape as well as describing features down to 1 µm [70]. This non-destructive technique can be used to image through whole scaffolds without staining, slicing, or drying out, which is beneficial to many biologically built materials [71–73].…”

Cartilage extracellular matrix as a biomaterial for cartilage regeneration

“…The aligned pores in both the DCC‐only and PLGA–DCC composite scaffolds guided the growth and orientation of the cells to mimic the structure of deep‐zone cartilage and enable cellular infiltration into the interior regions of the scaffold. Rowland et al . similarly adapted the decellularization procedure from Yang et al .…”