Nucleation and growth of mineralized bone matrix on silk-hydroxyapatite composite scaffolds

Abstract

We describe a composite hydroxyapatite (HA)-silk fibroin scaffold designed to induce and support the formation of mineralized bone matrix by human mesenchymal stem cells (hMSCs) in the absence of osteogenic growth factors. Porous three-dimensional silk scaffolds were extensively used in our previous work for bone tissue engineering and showed excellent biodegradability and biocompatibility. However, silk is not an osteogenic material and has a compressive stiffness significantly lower than that of native bone. In the present study, we explored the incorporation of silk sponge matrices with HA (bone mineral) micro-particles to generate highly osteogenic composite scaffolds capable of inducing the in vitro formation of tissue-engineered bone. Different amounts of HA were embedded in silk sponges at volume fractions of 0%, 1.6%, 3.1% and 4.6% to enhance the osteoconductive activity and mechanical properties of the scaffolds. The cultivation of hMSCs in the silk/HA composite scaffolds under perfusion conditions resulted in the formation of bone-like structures and an increase in the equilibrium Young's modulus (up to 4-fold or 8-fold over 5 or 10 weeks of cultivation, respectively) in a manner that correlated with the initial HA content. The enhancement in mechanical properties was associated with the development of the structural connectivity of engineered bone matrix. Collectively, the data suggest two mechanisms by which the incorporated HA enhanced the formation of tissue engineered bone: through osteoconductivity of the material leading to increased bone matrix production, and by providing nucleation sites for new mineral resulting in the connectivity of trabecular-like architecture.

Comparative study of porous hydroxyapatite/chitosan and whitlockite/chitosan scaffolds for bone regeneration in calvarial defects

“…[3][4][5] Hydroxyapatite (HAP; Ca 10 (PO 4 ) 6 (OH) 2 ), a major inorganic component of biological hard tissues such as bone and tooth, has been widely investigated for its application in bone tissue engineering owing to its excellent biocompatibility and biodegradability. [6][7][8][9] For example, Bhumiratana et al 10 explored the incorporation of silk sponge matrices with HAP microparticles to generate highly osteogenic composite scaffolds, which could induce in vitro bone formation. HAP embedded in silk sponges significantly enhanced the osteoconductive activity of the scaffolds, indicating that HAP has an outstanding bioactivity and is thus an ideal biomaterial for application in bone tissue engineering.…”

Effect of βTricalcium Phosphate Nanoparticles Additions on the Properties of Gelatin-Chitosan Scaffolds

“…Osteoinductive properties of porous hybrid scaffolds prepared from β-TCP, alginate-gelatin was reported elsewhere [16]. Functionally graded HA/silk fibroin biocomposite prepared by pulse electric current sintering [17,18] showed excellent mechanical strength and osteoconductivity. Le et al proposed that the physical, chemical and biological properties of calcium orthophosphate bioceramics and the fibrin glue might cumulate in biocomposites suitable for preparation of advanced bone grafts [19].…”

Assembly of complex cell microenvironments using geometrically docked hydrogel shapes

“…Human MSCs were isolated from fresh bone marrow aspirates obtained from Cambrex Life Sciences as previously described (38,50), grown in high-glucose DMEM with 10% (vol/vol) FBS and 1% penicillin/streptomycin (all from Invitrogen) with 0.1 ng/mL basic FGF (Invitrogen), and expanded to passage 8 or lower. Human umbilical vein endothelial cells were isolated from postnatal discarded umbilical veins and fully de-identified following the protocol IRB-AAAC4839 approved by the Columbia University Institutional Review Board, and grown using EGM-2 Media (Lonza) to passage 8 or lower.…”