Self-assembling RADA16 peptide hydrogel supports hemostasis, synechiae reduction, and wound healing in a sheep model of endoscopic nasal surgery

A Recombinant Human Collagen and RADA-16 Fusion Protein Promotes Hemostasis and Rapid Wound Healing

In this study, we designed a fusion protein, rhCR, by combining human collagen with the self-assembling peptide RADA-16 using genetic engineering technology. The rhCR protein was successfully expressed in Pichia pastoris. The rhCR can self-assemble into a three-dimensional nanofiber network under physiological conditions. The lyophilized rhCR sponge exhibited high elasticity modulus and stable swelling properties. In vitro experiments confirmed that the rhCR had good biocompatibility and could significantly promote the adhesion, proliferation, and migration of fibroblasts (L929), upregulating the expression of genes such as Vim, Fgf, Vegf, and Tgf-β3 in L929 cells. When applied to a mouse liver hemorrhage model, rhCR hemostatic sponges rapidly formed nanofibers on the ruptured liver surface, activated platelet CD62P, and significantly reduced blood loss and bleeding duration compared to the recombinant human collagen (rhCol) alone. Furthermore, the rhCR application markedly accelerated wound healing in a mouse full-thickness skin defect model, with the wound healing rate in the rhCR group being 2.6 times that of the untreated group and 1.7 times that of the rhCol group on day 6 postinjury. Histological and immunofluorescence analyses revealed that the rhCR promoted collagen deposition and epidermal regeneration and improved the quality of skin tissue repair by stimulating tissue cells to produce cytokines, growth factors, and immune factors through immunological regulation. The rhCR fusion protein combines the advantages of collagen and RADA-16, overcoming the limitations of their separate use in hemostatic and tissue engineering applications. This biomaterial and its design idea hold promise for a variety of regenerative applications.

Self-assembled Arginine-Glycine-Aspartic Acid Mimic Peptide Hydrogels as Multifunctional Biomaterials for Wound Healing

Clinical management of nonhealing ulcers requires advanced materials that can enhance wound closure rates without relying on the release of drugs or other growth factors to obviate systemic deleterious side effects. In our previous work, we synthesized an integrin-binding cell adhesive MNH2 {Fmoc-FFβAR(K)βA-NH2 consisting of an RGD mimic, [R(K)], with an amide terminus}, MOH {Fmoc-FFβAR(K)βA-OH consisting of an RGD mimic, [R(K)], with acid terminus}, and MR (Fmoc-FFβARGDβA-NH2 consisting of an RGD peptide, reference) with multifunctional activity. Here, we reported the synthesis, characterization, and performance of a reversed derivative, R-MNH2 (Fmoc-FFβA(K)RβA-NH2 consisting of an RGD mimic, [K(R)], with an amide terminus) of an antimicrobial cell adhesive peptide, MNH2. Both peptides (MNH2 and R-MNH2) were found to interact with αvβ3 integrin, as shown by docking studies; however, they differed in cell adhesive properties, hydrogel formation, and antimicrobial efficacy. Later, the wound healing ability of a series of RGD/RGD peptide mimics (MR, R-MNH2, MNH2, and MOH) was studied in a methicillin-resistant Staphylococcus aureus (MRSA)-infected Balb/c mouse model. All studied peptides showed cell adhesion and wound healing properties; however, only the amide-terminal RGD peptide mimic, MNH2, and its reversed derivative, R-MNH2, showed antimicrobial activity in both in vitro and in vivo studies. Of these, MNH2 showed the highest integrin-mediated spreading, migration, and proliferation of dermal cells in vitro as well as in vivo. Therefore, the MNH2 peptide mimic represents a paradigm shift in the development of dermoconductive strategies to treat chronic wounds.

Evaluation of sodium hyaluronate-based composite hydrogels for prevention of nasal adhesions

During the healing process after intra-nasal surgery, the growth and repair of damaged tissues can result in the development of postoperative adhesions. Various techniques have been devised to minimize the occurrence of postoperative adhesions which include insertion of stents in the middle meatus, application of removable nasal packing, and utilizing biodegradable materials with antiadhesive properties. This study assesses the efficacy of two sodium hyaluronate (SH)-based freeze-dried hydrogel composites in preventing postoperative nasal adhesions, comparing them with commonly used biodegradable materials in nasal surgery. The freeze-dried hydrogels, sodium hyaluronate and collagen 1(SH-COL1) and sodium hyaluronate, carboxymethyl cellulose, and collagen 1 (SH-CMC-COL1), were evaluated for their ability to reduce bleeding time, promote wound healing, and minimize fibrous tissue formation. Results showed that SH-CMC-COL1 significantly reduced bleeding time compared to both biodegradable polyurethane foam and SH-COL1. Both SH-COL1 and SH-CMC-COL1 exhibited enhanced wound healing effects, as indicated by significantly greater wound size reduction after two weeks compared to the control. Histological analyses revealed significant differences in re-epithelialization and blood vessel count among all tested materials, suggesting variable initial wound tissue response. Although all treatment groups had more epithelial growth, with X-SCC having higher blood vessel count at 7 d post treatment, all treatment groups did not differ in all histomorphometric parameters by day 14. However, the long-term application of SH-COL1 demonstrated a notable advantage in reducing nasal adhesion formation compared to all other tested materials. This indicates the potential of SH-based hydrogels, particularly SH-COL1, in mitigating postoperative complications associated with nasal surgery. These findings underscore the versatility and efficacy of SH-based freeze-dried hydrogel composites for the management of short-term and long-term nasal bleeding with an anti-adhesion effect. Further research is warranted to optimize their clinical use, particularly in understanding the inflammatory factors influencing tissue adhesions and assessing material performance under conditions mimicking clinical settings. Such insights will be crucial for refining therapeutic approaches and optimizing biomaterial design, ultimately improving patient outcomes in nasal surgery.

Functional hemostatic hydrogels: design based on procoagulant principles

Uncontrolled hemorrhage results in various complications and is currently the leading cause of death in the general population. Traditional hemostatic methods have drawbacks that may lead to ineffective hemostasis and even the risk of secondary injury. Therefore, there is an urgent need for more effective hemostatic techniques. Polymeric hemostatic materials, particularly hydrogels, are ideal due to their biocompatibility, flexibility, absorption, and versatility. Functional hemostatic hydrogels can enhance hemostasis by creating physical circumstances conducive to hemostasis or by directly interfering with the physiological processes of hemostasis. The procoagulant principles include increasing the concentration of localized hemostatic substances or establishing a physical barrier at the physical level and intervention in blood cells or the coagulation cascade at the physiological level. Moreover, synergistic hemostasis can combine these functions. However, some hydrogels are ineffective in promoting hemostasis or have a limited application scope. These defects have impeded the advancement of hemostatic hydrogels. To provide inspiration and resources for new designs, this review provides an overview of the procoagulant principles of hemostatic hydrogels. We also discuss the challenges in developing effective hemostatic hydrogels and provide viewpoints.

Short Peptide Nanofiber Biomaterials Ameliorate Local Hemostatic Capacity of Surgical Materials and Intraoperative Hemostatic Applications in Clinics

Short designer self-assembling peptide (dSAP) biomaterials are a new addition to the hemostat group. It may provide a diverse and robust toolbox for surgeons to integrate wound microenvironment with much safer and stronger hemostatic capacity than conventional materials and hemostatic agents. Especially in noncompressible torso hemorrhage (NCTH), diffuse mucosal surface bleeding, and internal medical bleeding (IMB), with respect to the optimal hemostatic formulation, dSAP biomaterials are the ingenious nanofiber alternatives to make bioactive neural scaffold, nasal packing, large mucosal surface coverage in gastrointestinal surgery (esophagus, gastric lesion, duodenum, and lower digestive tract), epicardiac cell-delivery carrier, transparent matrix barrier, and so on. Herein, in multiple surgical specialties, dSAP-biomaterial-based nano-hemostats achieve safe, effective, and immediate hemostasis, facile wound healing, and potentially reduce the risks in delayed bleeding, rebleeding, post-operative bleeding, or related complications. The biosafety in vivo, bleeding indications, tissue-sealing quality, surgical feasibility, and local usability are addressed comprehensively and sequentially and pursued to develop useful surgical techniques with better hemostatic performance. Here, the state of the art and all-round advancements of nano-hemostatic approaches in surgery are provided. Relevant critical insights will inspire exciting investigations on peptide nanotechnology, next-generation biomaterials, and better promising prospects in clinics.