An in vitro analysis of the hemostatic efficacy of fibrinogen precipitation with varied keratin fraction compositions.

In preclinical studies, human hair has demonstrated effective hemostatic properties, potentially attributed to keratin proteins facilitating rapid conversion of fibrinogen to fibrin during coagulation. However, the rational use of human hair keratin for hemostasis remains unclear, given its complex mixture of proteins with diverse molecular weights and structures, leading to variable hemostatic capacity. To optimize the rational utilization of human hair keratin for hemostasis, we investigated the effects of different keratin fractions on keratin-mediated fibrinogen precipitation using a fibrin generation assay. Our study focused on high molecular weight keratin intermediate filaments (KIFs) and lower molecular weight keratin-associated proteins (KAPs) combined in various ratios during the fibrin generation. Scanning electron microscope analysis of the precipitates revealed a filamentous pattern with a broad distribution of fiber diameters, likely due to the diversity of keratin mixtures involved. An equal proportion of KIFs and KAPs in the mixture yielded the most extensive precipitation of soluble fibrinogen in an in vitro study, potentially due to structure-induced exposure of active sites. However, all hair protein samples exhibited diverse catalytic behaviors compared to thrombin, highlighting the potential of utilizing specific hair fractions to develop hair protein-based hemostatic materials with optimized capacity.

Effect of thermal treatments on the structural change and the hemostatic property of hair extracted proteins.

Human hair is a readily available source for hair protein-based biomaterial and is increasingly explored as an alternative to existing hemostatic materials. The hair protein is a complex mixture of multiple proteins, which are preferably extracted at relatively high temperatures (50-90 °C) for increasing protein yields. However, the effect of processing temperature on the hemostatic property of the hair derived proteins are not yet well-understood. The objective of the current study was to characterize the influence of thermal treatments (37 °C, 50 °C, 75 °C, 80 °C, and 90 °C) on the (i) secondary structure of different fractions of hair proteins including keratin (40-65 kDa) and keratin-associated proteins (KAPs, 6-30 kDa), and (ii) their capability to precipitate the soluble fibrinogen in an in vitro fibrin clotting assay. Our results indicated that the thermal treatments induced changes to the helical contents of hair-derived protein extracts and also increased the precipitation amount and rate of soluble fibrinogen. While further studies are required to better understand the exact role of hair protein fractions on the coagulation process, the current research suggests that the hair proteins extracted under relatively high temperatures is a prerequisite approach for improving the hemostatic property of human hair-derived proteins.