Novel keratin preparation supports growth and differentiation of odontoblast-like cells.

AIM: To fabricate a keratin hydrogel, characterize its functionality as a biomaterial and investigate the effects of keratin on growth and differentiation of odontoblast-like cells. METHODOLOGY: Keratins were extracted from sheep wool using a well-established technique. The extracted proteins were purified by dialysis, quantified by gel electrophoresis, mass spectrometry, amino acid analysis and inductively coupled mass spectrometry. The microstructure of the fabricated keratin hydrogels was studied by scanning electron microscopy, flow characteristics by rheometer, hydrolytic stability and cytocompatibility by Live/Dead(®) cell assay. Furthermore, the influence of keratin on odontoblast-like cells (MDPC-23) was assessed to confirm their bioactivity at different dilutions. Cell proliferation was studied using alamarBlue(®) assay and differentiation by alkaline phosphatase enzyme activity, alizarin red staining and calcium quantification, reverse transcription polymerase chain reaction (rt-PCR) and immunocytochemical staining for dentine matrix protein- 1 (DMP-1) expression. anova with Tukey's tests was performed for statistical comparison. RESULTS: The characterized hydrogel was injectable with a highly porous architecture that underwent slow degradation, and its cytocompatibility was statistically equivalent to collagen hydrogel (P > 0.05). Cell proliferation and differentiation were enhanced at the optimal keratin concentration of 0.1 mg mL(-1) . At this concentration, the influence of keratin on cell differentiation was demonstrated by marked elevation in alkaline phosphatase activity (P < 0.05), calcium deposition (P < 0.01), gene expression (P < 0.01) and positive immunostaining for DMP-1. CONCLUSION: The presence of keratin enhanced odontoblast cell behaviour. Keratin hydrogels may be a potential scaffold for pulp-dentine regen-eration.

Osteoprotective Effects of Estrogen in the Maxillary Bone Depend on ERα.

Estrogen deficiency results in disruption of maxillary alveolar bone microarchitecture. Most of the actions of estrogen in long bones occur via estrogen receptor α (ERα). However, the function of ERα in the maxillary bone has not been defined. We aimed to investigate the role and underlying mechanisms of ERα in the physiological and mechanically induced alveolar bone remodeling in female and male mice. Wild-type (WT) and ERα(-/-) (ERKOα) mice were subjected to mechanically stimulated bone remodeling by inducing orthodontic tooth movement (OTM). The maxillary bone was analyzed using histomorphometric analysis, micro-computed tomography, quantitative polymerase chain reaction, and energy-dispersive spectroscopy. Bone marrow cells (BMCs) from WT and ERKOα mice were tested for their capacity to differentiate into osteoblasts and osteoclasts. Both male and female ERKOα mice exhibited marked reduction of alveolar bone mass and increased OTM. This response was associated with an increased number of osteoclasts and reduced number of apoptotic cells and osteoblasts in the periodontium and alveolar bone. Consistently, ERKOα mice exhibited lower levels of calcium in bone and increased expression of IL-33 (interleukin-33), TNF-α (tumor necrosis factor α), and IL-1ß (interleukin-1ß) and decreased expression of dentin matrix acidic phosphoprotein and alkaline phosphatase in periodontal tissues. Moreover, the differentiation of osteoclasts and osteoblasts in vitro was significantly higher in BMCs obtained from ERKOα. ERα is required to maintain the microarchitecture of maxillary alveolar bone. This process is linked to bone cell differentiation and apoptosis, as well as local production of inflammatory molecules such as IL-33, TNF-α, and IL-1ß.