The enrichment of whey protein isolate hydrogels with Poly-γ-glutamic acid promotes the proliferation and osteogenic differentiation of pre-osteoblasts

Baines, Daniel and Platania, Varvara and Tavernaraki, Nikoleta and Parati, Mattia and Wright, Karen and Radecka, Iza and Chatzinikolaidou, Maria and Douglas, Timothy (2023) The enrichment of whey protein isolate hydrogels with Poly-γ-glutamic acid promotes the proliferation and osteogenic differentiation of pre-osteoblasts. Gels, 10 (1): 18. ISSN 2310-2861

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Abstract

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.