Imunofan-RDKVYR Peptide-Stimulates Skin Cell Proliferation and Promotes Tissue Repair

Release systems based on self-assembling RADA16-I hydrogels with a signal sequence which improves wound healing processes

Self-assembling peptides can be used for the regeneration of severely damaged skin. They can act as scaffolds for skin cells and as a reservoir of active compounds, to accelerate scarless wound healing. To overcome repeated administration of peptides which accelerate healing, we report development of three new peptide biomaterials based on the RADA16-I hydrogel functionalized with a sequence (AAPV) cleaved by human neutrophil elastase and short biologically active peptide motifs, namely GHK, KGHK and RDKVYR. The peptide hybrids were investigated for their structural aspects using circular dichroism, thioflavin T assay, transmission electron microscopy, and atomic force microscopy, as well as their rheological properties and stability in different fluids such as water or plasma, and their susceptibility to digestion by enzymes present in the wound environment. In addition, the morphology of the RADA-peptide hydrogels was examined with a unique technique called scanning electron cryomicroscopy. These experiments enabled us to verify if the designed peptides increased the bioactivity of the gel without disturbing its gelling processes. We demonstrate that the physicochemical properties of the designed hybrids were similar to those of the original RADA16-I. The materials behaved as expected, leaving the active motif free when treated with elastase. XTT and LDH tests on fibroblasts and keratinocytes were performed to assess the cytotoxicity of the RADA16-I hybrids, while the viability of cells treated with RADA16-I hybrids was evaluated in a model of human dermal fibroblasts. The hybrid peptides revealed no cytotoxicity; the cells grew and proliferated better than after treatment with RADA16-I alone. Improved wound healing following topical delivery of RADA-GHK and RADA-KGHK was demonstrated using a model of dorsal skin injury in mice and histological analyses. The presented results indicate further research is warranted into the engineered peptides as scaffolds for wound healing and tissue engineering.

Examination of epigenetic inhibitor zebularine in treatment of skin wounds in healthy and diabetic mice

DNA methyltransferase inhibitor zebularine was proven to induce regeneration in the ear pinna in mice. We utilized a dorsal skin wound model to further evaluate this epigenetic inhibitor in wound healing. Full-thickness excisional wounds were made on the dorsum of 2 and 10-month-old healthy BALB/c and 3 and 8-month-old diabetic (db/db) mice, followed by topical or intraperitoneal zebularine delivery. Depending on the strain, age, dose, and delivery, the zebularine treatments either had no effect or accelerated or delayed wound closure. In principle, zebularine applied topically moderately promoted wound closure in the healthy but markedly delayed in the diabetic mice, which was in line with decreased viability of cultured keratinocytes from diabetic patients exposed to zebularine. The histological analysis revealed an improvement in the architecture of restored skin in zebularine-treated mice, manifested as a distinct layered pattern resembling panniculus carnosus. The finding corresponds with the zebularine-mediated activation of the Wnt5a gene, an essential regulator of Wnt signaling, the pathway involved in hair follicle development, the process which in turn is connected with regenerative skin healing. Although zebularine did not remarkably accelerate wound healing, zebularine and other epigenetic inhibitors deserve further testing as potential drugs to improve the quality of restored skin.

Evaluation of Morphological and Histological Changes of Aggregated Lymph Nodes in the Small Intestine after Imofan Treatment in Immunosuppressed Rats

Diffuse nodular lymphoid hyperplasia is a rare gastrointestinal disease that can be diagnosed by multiple nodules in the small intestine, large intestine, or both. Immunodeficiency and infections are the common situations that lead to the diffusion of nodular lymphoid hyperplasia. For instance, Giardia lamblia and Helicobacter pylori are the major pathogens leading to this disorder. Diffuse nodular lymphoid hyperplasia leads to allergic reactions, immunodeficiency, and autoimmune diseases. Imunofan-RDKVYR Peptide-is a potential agent in regenerative medicine. The present study aimed to investigate morphological features of the aggregated lymphoid nodules of the small intestine after the Imunofan (IM) administration following Cyclophosphamide-induced immunosuppression. In total, 72 Wistar male rats were randomly divided into two groups (n=36). Group I was considered the control group, and group II was subjected to intramuscular injections (needle 21 G) of0.2 ml of normal saline following the Cyclophosphamide-induced immunosuppression on the 2nd, 4th, 6th, 8th, and 10th days of the experiment. The animals in group II were injected with Cyclophosphamide at a dose of 200 mg/kg bodyweight to induce immunosuppression. The animals in the experimental group (n=36) were subjected to intramuscular injections (needle 21 G) of the 0.2 ml IM at a dose of 0.7μg/kg body weight on the 2nd, 4th, 6th, 8th, 10th days of the experiment. The results of the study indicated that on the 7th day in group II, the length and width of the aggregated lymphoid nodules increased, as well as the height and width of the lymphoid nodules and internodular zones as structural components of the lymphoid formations in the small intestine. In group I, by the 30th day of the experiment, the linear dimensions of the aggregated lymphoid nodules exceeded, but to a lesser extent than on the 7th day of the experiment which explains the ability of IM to neutralize the effects of Cyclophosphamide. It should also be noted that the IM was performed to regenerate damaged cells which helped maintain the population of lymphocytes in the limb and led to an increase in linear dimensions (length and width) not only between the joint but also in the lymph nodes.

Functionalized Peptide Fibrils as a Scaffold for Active Substances in Wound Healing

Technological developments in the field of biologically active peptide applications in medicine have increased the need for new methods for peptide delivery. The disadvantage of peptides as drugs is their low biological stability. Recently, great attention has been paid to self-assembling peptides that can form fibrils. Such a formulation makes bioactive peptides more resistant to enzymatic degradation and druggable. Peptide fibrils can be carriers for peptides with interesting biological activities. These features open up prospects for using the peptide fibrils as long-acting drugs and are a valid alternative to conventional peptidic therapies. In our study, we designed new peptide scaffolds that are a hybrid of three interconnected amino acid sequences and are: pro-regenerative, cleavable by neutrophilic elastase, and fibril-forming. We intended to obtain peptides that are stable in the wound environment and that, when applied, would release a biologically active sequence. Our studies showed that the designed hybrid peptides show a high tendency toward regular fibril formation and are able to release the pro-regenerative sequence. Cytotoxicity studies showed that all the designed peptides were safe, did not cause cytotoxic effects and revealed a pro-regenerative potential in human fibroblast and keratinocyte cell lines. In vivo experiments in a dorsal skin injury model in mice indicated that two tested peptides moderately promote tissue repair in their free form. Our research proves that peptide fibrils can be a druggable form and a scaffold for active peptides.