Biomimetic Collagen–Hydroxyapatite Composite Fabricated via a Novel Perfusion-Flow Mineralization Technique

Abstract

Prevalent three-dimensional scaffolds for bone tissue engineering are mineralized collagen-hydroxyapatite (Col/HA) composites. Conventional mineralization techniques are either to coat collagen scaffold surfaces with minerals or to simply mix collagen and mineral nanoparticles together. These conventional in vitro collagen mineralization methods are different from the in vivo bone formation process and often result in scaffolds that are not suitable for bone tissue engineering. In this study, a unique perfusion-flow (i.e., dynamic) in conjunction with a previously described polymer-induced liquid-precursor (PILP) method was used to fabricate a porous Col/HA composite. The dynamic flow emulated the physiological extracellular fluid flow containing the mineralization ions, while the PILP method facilitated the deposition of the HA crystals within the collagen fibrils (i.e., intrafibrillar mineralization). By utilizing a dynamic PILP technique to mimic the in vivo bone formation process, the resultant Col/HA composite has a similar structure and compositions like human trabecular bone. A comparison of the dynamic and static mineralization methods revealed that the novel dynamic technique facilitates more efficient and homogenous mineral deposition throughout the Col/HA composite. The dynamic intrafibrillar mineralization method generated stiff Col/HA composites with excellent surface property for cell attachment and growth. The human mesenchymal stem cells cultured on the Col/HA composites quickly remodeled the scaffolds and resulted in constructs with an extensive cell-derived extracellular matrix network.

Stromal-Cell-Derived Extracellular Matrix Promotes the Proliferation and Retains the Osteogenic Differentiation Capacity of Mesenchymal Stem Cells on Three-Dimensional Scaffolds

“…This fact was further corroborated by measuring overall construct porosity using helium pycnometry before and after ECM deposition. 35 It was shown that without ECM the overall porosity of the Co/HA scaffold…”

“…The preparation and properties of the Col/HA scaffolds were described in our previous work. 35 Prior to cell studies, the Col/HA discs were sterilized with ethylene oxide and subsequently prehydrated in media overnight at 37°C. Approximately 1 · 10 5 P.3 MSCs were seeded on top of the scaffolds and incubated for 1 h in a 37°C cell-culture incubator allowing cells to attach.…”

“…26,29 In our previous work, the design and fabrication of a biomimetic collagen/hydroxyapatite (Col/HA) composite scaffold was described. 35 The Col/HA scaffold exhibited properties similar to that of trabecular bone in terms of tissue architecture and composition. It was demonstrated that through its interconnected pore design and high ( > 95%) overall porosity, the Col/HA scaffold was highly biocompatible for prolonged culture of MSCs.…”

Synergistic intrafibrillar/extrafibrillar mineralization of collagen scaffolds based on a biomimetic strategy to promote the regeneration of bone defects

“…[1][2][3][4][5][6][7] Among these biomaterials, type 1 9 To date, mixing collagen with minerals and mineralizing collagen have been used to modify collagen scaffolds for simulating the composition and microstructure of bone tissue to the greatest extent possible. [10][11][12][13][14][15][16][17] Because HA is a primary mineral component of natural bone and possesses outstanding bioactivity, osteoconductivity, biocompatibility with bone cells, good mechanical properties, and a slow degradation rate in vivo, it has often been the first choice for modifying collagen scaffolds. 10,[18][19][20] Although directly mixing collagen with HA powders in certain proportions can result in collagen scaffolds with compositions similar to those of natural bone tissues, it is difficult to simulate their microstructure and microenvironment via this process.…”

On Mineral Retrosynthesis of a Complex Biogenic Scaffold

“…The polymer-induced liquid precursor (PILP) phase stabilized by PAA exhibits liquid-like properties and is suggested to be drawn into the gaps within collagen fibrils by capillary effects. On crystallization, the collagenous matrix encloses organized assemblies of hydroxyapatite nanoparticles formed on phase transformation [38]. Mineralization of the insoluble matrix of nacre material in the presence of PAA also reports morphologies structurally analogous to the natural biomineral [39].…”