High Molecular Weight Poly(glutamic acid) to Improve BMP2-Induced Osteogenic Differentiation

The Enrichment of Whey Protein Isolate Hydrogels with Poly-γ-Glutamic Acid Promotes the Proliferation and Osteogenic Differentiation of Preosteoblasts

Osseous disease accounts for over half of chronic pathologies, but there is a limited supply of autografts, the gold standard; hence, there is a demand for new synthetic biomaterials. Herein, we present the use of a promising, new dairy-derived biomaterial: whey protein isolate (WPI) in the form of hydrogels, modified with the addition of different concentrations of the biotechnologically produced protein-like polymeric substance poly-γ-glutamic acid (γ-PGA) as a potential scaffold for tissue regeneration. Raman spectroscopic analysis demonstrated the successful creation of WPI-γ-PGA hydrogels. A cytotoxicity assessment using preosteoblastic cells demonstrated that the hydrogels were noncytotoxic and supported cell proliferation from day 3 to 14. All γ-PGA-containing scaffold compositions strongly promoted cell attachment and the formation of dense interconnected cell layers. Cell viability was significantly increased on γ-PGA-containing scaffolds on day 14 compared to WPI control scaffolds. Significantly, the cells showed markers of osteogenic differentiation; they synthesised increasing amounts of collagen over time, and cells showed significantly enhanced alkaline phosphatase activity at day 7 and higher levels of calcium for matrix mineralization at days 14 and 21 on the γ-PGA-containing scaffolds. These results demonstrated the potential of WPI-γ-PGA hydrogels as scaffolds for bone regeneration.

The optimal scaffold for silk sericin-based bone graft: collagen versus gelatin

BACKGROUND

Silk sericin is an active ingredient in bone grafts. However, the optimal scaffold for silk sericin has yet to be identified.

METHOD

A critical-sized bone defect model in rat calvaria was used to evaluate bone regeneration. Silk sericin from Yeonnokjam, Bombyx mori, was incorporated into gelatin (group G, n = 6) and collagen (group C, n = 6). Bone regeneration was evaluated using micro-computed tomography (mCT) and histology.

RESULTS

Group C showed a larger bone volume than group G in the mCT analysis (P = 0.001). Histological analysis showed a larger area of bony defects in group G than in group C. The bone regeneration area in group C was significantly larger than that in group G (P = 0.003).

CONCLUSION

Compared with gelatin, collagen shows better bone regeneration in silk sericin-based bone grafts.