Protein-based biomaterials are widely used in tissue engineering and regenerative medicine; however, many conventional materials suffer from limitations including immunogenicity, low stability, and risks associated with animal-derived sources. In this context, keratin derived from human hair has attracted increasing attention due to its inherent biocompatibility and cysteine-rich structure, which provides reactive thiol (-SH) groups suitable for chemical modification. In the present study, reductively extracted keratin was utilized to preserve thiol functionality, enabling site-selective modification via thiol-maleimide chemistry using an aminoethyl maleimide (AEM) linker. Through this approach, heparin, a clinically established anticoagulant, was immobilized onto keratin films under mild aqueous conditions. The resulting keratin-heparin films exhibited effective suppression of thrombin-induced coagulation, whereas unmodified keratin showed no anticoagulant activity. Furthermore, spectroscopic and colorimetric analyses confirmed successful heparin conjugation and surface presentation, and no measurable heparin release was detected, indicating stable surface immobilization. Overall, these results demonstrate that thiol-specific functionalization provides a selective, stable, and animal-free platform for anticoagulant surface modification, highlighting the potential of keratin-based materials for blood-contacting biomedical applications.
Introduction: We previously reported that hesperidin intake reduces blood pressure (BP) in 2-kidney, 1-clip renovascular hypertensive model (2K1C) rats. Hesperidin is a kind of polyphenol found in citrus peels, and was reported to contribute to the proliferation of bacteria such as Bifidobacterium spp ., Lactobacillus spp ., and Akkermansia muciniphila , which produce short-chain fatty acids (SCFAs). SCFAs such as acetic acid, butyric acid and propionic acid, have been reported to lower BP in hypertensive model animals. However, to our knowledge, there have been no studies that observed changes in their gut microbiota in hypertensive model animals when administered hesperidin. Hypothesis: Hesperidin partially alters gut microbiota, especially with an increase in SCFA-producing bacteria in 2K1C rats. Methods: Sham-operated control model (SHAM) or 2K1C were induced in six-week-old Sprague Dawley rats under anesthesia. Both rat models were made to ingest a control diet (CTL) or a 0.1% (0.1 of 100, w/w) hesperidin including diet (Hes), and to access a drinking water freely for 6 weeks. During the feeding, rats were observed systolic BP (SBP) by tail-cuff method weekly. After euthanasia, the cecal contents were collected and analyzed for microbiota by 16S rRNA amplicon sequencing V3-V4 hypervariable regions. P < 0.05 was considered statistically significant. Results: Six weeks after surgery, the SBP was significantly higher in 2K1C-CTL than that of SHAM-CTL (178 ± 5 vs 133 ± 3 mmHg, P < 0.001) and was significantly lower in 2K1C-Hes (158 ± 2 mmHg, P < 0.01) than that of 2K1C-CTL. In SHAM, there was no significant difference in SBP between CTL and Hes groups (133 ± 3 and 132 ± 3 mmHg). The Kruskal-Wallis test revealed significant differences in the relative abundance of Eubacterium , Acetitomaculum and Blautia among 4 groups: SHAM or 2K1C rats fed CTL or Hes . Subsequently, post-hoc tests showed that the relative abundance of Acetitomaculum and Blautia were significantly increased in 2K1C-Hes compared with 2K1C-CTL. Because Acetitomaculum and Blautia are SCFA-producing bacteria, their increases may contribute to the suppression of BP elevation in 2K1C rats. Conclusions: Hesperidin intake partially altered the gut microbiota in 2K1C rats, with a significant increase in SCFA-producing bacteria including Acetitomaculum and Blautia .
Introduction: We previously observed a decrease in blood pressure (BP) by intake of Saccharina japonica (SJ) or the extract of SJ (SJE) diet in 2-kidney, 1-clip renovascular hypertensive (2K1C) rats. SJ is rich in glutamate (Glu) and aspartate (Asp), which are the umami taste of amino acids. Over 70% (70 of 100) of the SJ components such as Glu and Asp are eluted into the SJE from SJ. It was reported that people with a high dietary intake of Glu have lower BP in epidemiological studies. The intake of Asp was reported to reduce BP in Dahl salt-sensitive rats. Therefore, we hypothesized that the intake of Glu and Asp reduces BP in 2K1C rats. To test the hypothesis, we observed BP in renovascular hypertensive rats fed Glu. Then, we also observed the effect of nitric oxide synthase (NOS) inhibitors in order to investigate the involvement of NOS in the mechanism. We also observed the BP in 2K1C rats ingested Asp. Methods: Male Sprague-Dawley rats (6 wks) were treated with sham surgery (SHAM) or left renal artery clipping (2K1C). These rats were fed a control diet (C) or a Glu-supplemented diet (G), with tap water (V) or neuronal NOS (nNOS) inhibitor (7NI). In another experiment, SHAM or 2K1C rats were fed a control diet (C) or a Asp-supplemented diet for 6 weeks, respectively. Systolic BP (SBP) and mean arterial BP (MAP) were measured. Results: SBP of 6 weeks after the surgery was significantly increased in the 2K1C-C group than in the SHAM-C group (111±6 vs 163±3 mmHg, p < 0.05). In the SHAM and 2K1C of G groups, BP significantly increased compared with each C group (111±6 vs 147±3 and 163±3 vs 177±7, p < 0.05). In group C, SBP of SHAM-7NI was significantly higher than SHAM-V(152±4 vs 111±6, p < 0.05) but not in 2K1C groups. On the other hands in the G groups fed a Glu diet, there was no difference in SBP between the SHAM-7NI and -V, but 2K1C-7NI was significantly lower than 2K1C-V (149±4 vs 147±3 and 165±4 vs 182±7, p < 0.05). Besides, 2K1C-Asp decreased compared with 2K1C-C (147±4 vs 161±4 mmHg, p < 0.05), while there was no difference among SHAM groups. The MAP was observed to be consistent with those of SBP. Discussion and conclusions: These results suggest that Glu increases BP in renovascular hypertensive rats a mechanism involving the activation of nNOS, whereas that significantly increase BP in normotensive SHAM rats without involving the nNOS activation. In contrast, Asp is probably attenuate hypertension in 2K1C renovascular hypertension.
