Injectable conductive hydrogel remodeling microenvironment and mimicking neuroelectric signal transmission after spinal cord injury.

Severe spinal cord injury (SCI) leads to dysregulated neuroinflammation and cell apoptosis, resulting in axonal die-back and the loss of neuroelectric signal transmission. While biocompatible hydrogels are commonly used in SCI repair, they lack the capacity to support neuroelectric transmission. To overcome this limitation, we developed an injectable silk fibroin/ionic liquid (SFMA@IL) conductive hydrogel to assist neuroelectric signal transmission after SCI in this study. The hydrogel can form rapidly in situ under ultraviolet (UV) light. The mechanical supporting and neuro-regenerating properties are provided by silk fibroin (SF), while the conductive capability is provided by the designed ionic liquid (IL). SFMA@IL showed attractive features for SCI repair, such as anti-swelling, conductivity, and injectability. In vivo, SFMA@IL hydrogel used in rats with complete transection injuries was found to remodel the microenvironment, reduce inflammation, and facilitate neuro-fiber outgrowth. The hydrogel also led to a notable decrease in cell apoptosis and the achievement of scar-free wound healing, which saved 45.6 ± 10.8 % of spinal cord tissue in SFMA@IL grafting. Electrophysiological studies in rats with complete transection SCI confirmed SFMA@IL's ability to support sensory neuroelectric transmission, providing strong evidence for its signal transmission function. These findings provide new insights for the development of effective SCI treatments.

Multi-scale, multi-level anisotropic silk fibroin/metformin scaffolds for repair of peripheral nerve injury.

Silk fibroin (SF) as a natural polymer has a long history of application in various regenerative medicine fields, but there are still many shortcomings in silk fibroin for using as nerve scaffolds, which limit its clinical application in peripheral nerve regeneration (PNR). In this work, a multi-scale and multi-level metformin (MF)-loaded silk fibroin scaffold with anisotropic micro-nano composite topology was prepared by micromolding electrospinning for accelerating PNR. The scaffolds were characterized for morphology, wettability, mechanical properties, degradability, and drug release, and Schwann cells (SCs) and dorsal root ganglia (DRG) were cultured on the scaffolds to assess their effects on neural cell behavior. Finally, the gene expression differences of neural cells cultured on scaffolds were analyzed by gene sequencing and RT-qPCR to explore the possible signaling pathways and mechanisms. The results showed that the scaffolds had excellent mechanical properties and hydrophilicity, slow degradation rate and drug release rate, which were enough to support the repair of peripheral nerve injury for a long time. In Vitro cell experiments showed that the scaffolds could significantly promote the orientation of SCs and axons extension of DRG. Gene sequencing and RT-qPCR revealed that the scaffolds could up-regulate the expression of genes related to SCs proliferation, adhesion, migration, and myelination. In summary, the scaffolds hold great potential for promoting PNR at the micro/nano multiscale and physical/chemical levels and show promising application for the treatment of peripheral nerve injury in the future.

Metformin loaded injectable silk fibroin microsphere for the treatment of spinal cord injury.

The repair of spinal cord injury is a great challenge in clinical. Improving the microenvironment of the injured site is the key strategy for accelerating axon regeneration and synaptic formation. Herein, a kind of silk fibroin microspheres functionalized by metformin through dopamine was developed using water-in-oil emulsification-diffusion method and surface modification technique, and the effect on cortical neuron was evaluated. The results showed that the microspheres showed a uniform size distribution with the diameter of around 60 µm and a concave structure. Moreover, the microspheres possessed good injectability and stability. In addition, the metformin could be successfully immobilized in the silk fibroin microspheres. The cell culture results displayed that the growth and morphology of cortical neurons on the microspheres with metformin concentration of 5 mg/mL and 10 mg/mL were obviously better than that on other samples. Notably, the spread area of single cortical cell on silk fibroin microspheres was increased with the ascending metformin concentration. Therefore, the results indicated that the metformin loaded silk fibroin microsphere could obviously improve the growth and spreading behavior of cortical neuron. The study may provide an important experimental basis for the development of drug loaded injectable biomaterials scaffolds for the treatment of spinal cord injury and have great potential for spinal cord regeneration.

Silk fibroin nanocomposites as tissue engineering scaffolds - A systematic review.

Silk fibroin is a protein with intrinsic characteristics that make it a good candidate as a scaffold for tissue engineering. Recent works have enhanced its benefits by adding inorganic phases that interact with silk fibroin in different ways. A systematic review was performed in four databases to study the physicochemical and biological performance of silk fibroin nanocomposites. In the last decade, only 51 articles contained either in vitro cell culture models or in vivo tests. The analysis of such works resulted in their classification into the following scaffold types: particles, mats and textiles, films, hydrogels, sponge-like structures, and mixed conformations. From the physicochemical perspective, the inorganic phase imbued in silk fibroin nanocomposites resulted in better stability and mechanical performance. This review revealed that the inorganic phase may be associated with specific biological responses, such as neovascularisation, cell differentiation, cell proliferation, and antimicrobial and immunomodulatory activity. The study of nanocomposites as tissue engineering scaffolds is a highly active area mostly focused on bone and cartilage regeneration with promising results. Nonetheless, there are still many challenges related to their application in other tissues, a better understanding of the interaction between the inorganic and organic phases, and the associated biological response.

Molecular mechanisms of esophageal epithelial regeneration following repair of surgical defects with acellular silk fibroin grafts.

Constructive remodeling of focal esophageal defects with biodegradable acellular grafts relies on the ability of host progenitor cell populations to repopulate implant regions and facilitate growth of de novo functional tissue. Intrinsic molecular mechanisms governing esophageal repair processes following biomaterial-based, surgical reconstruction is largely unknown. In the present study, we utilized mass spectrometry-based quantitative proteomics and in silico pathway evaluations to identify signaling cascades which were significantly activated during neoepithelial formation in a Sprague Dawley rat model of onlay esophagoplasty with acellular silk fibroin scaffolds. Pharmacologic inhibitor and rescue experiments revealed that epithelialization of neotissues is significantly dependent in part on pro-survival stimuli capable of suppressing caspase activity in epithelial progenitors via activation of hepatocyte growth factor receptor (c-MET), tropomyosin receptor kinase A (TrkA), phosphoinositide 3-kinase (PI3K), and protein kinase B (Akt) signaling mechanisms. These data highlight the molecular machinery involved in esophageal epithelial regeneration following surgical repair with acellular implants.

Toxicological assessment and food allergy of silk fibroin derived from Bombyx mori cocoons.

Recent studies have demonstrated silk fibroin protein's (SF) ability to extend the shelf life of foods by mitigating the hallmarks of spoilage, namely oxidation and dehydration. Due to the potential for this protein to become more widespread, its safety was evaluated comprehensively. First, a bacterial reverse mutation test (Ames test) was conducted in five bacterial strains. Second, an in vivo erythrocyte test was conducted with Sprague Dawley rats at doses up to 1,000mg/kg-bw/day. Third, a range-finder study was conducted with Sprague Dawley rats at the highest consumption amount given solubility and oral gavage volume constrains (500mg/kg-bw/day). Fourth, a 28-day sub-chronic study in Sprague Dawley rats was conducted with the high dose set at 500mg/kg-bw/day, as limited by solubility of the protein in a single-gavage per-day study. Fifth, an in vitro pepsin digestion assay was performed to assess the potential for protein allergenicity. Sixth, allergenic potential was further assessed using liquid chromatography-mass spectroscopy for detection of allergenic insect proteins. Seventh, the SF protein sequences were subjected to bioinformatic analyses. Together, these studies raise no mutagenic, genotoxic, toxicological, or allergenic concerns with the oral consumption of silk fibroin.

Antibacterial Vitamin K3 Carnosine Peptide-Laden Silk Fibroin Electrospun Fibers for Improvement of Skin Wound Healing in Diabetic Rats.

The utilization of a multifunctional bioactive molecule functionalized electrospun dressing in tissue repair and regenerative function is a prominent therapeutic strategy for preparing efficient biomaterials to promote chronic wound healing. Designing robust and highly efficient antibacterial agents in resistance against microbes and bacterial infections is a key challenge for accelerating diabetic wound healing until today. In this study, we developed a vitamin K3 carnosine peptide (VKC)-laden silk fibroin electrospun scaffold (SF-VKC) for diabetic wound healing. The structural confirmation of synthesized VKC was characterized by 1H NMR, 13C NMR, electrospray ionization mass spectrometry (ESI-MS), and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy analysis, and the cell viability of VKC was evaluated by the CCK-8 assay in HFF1 and NIH 3T3 cells. VKC shows excellent cell viability on both cell lines, and the VKC and SF-VKC electrospun mats exhibited excellent antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Prepared SF and SF-VKC fibrous mats were well characterized, and the SF-VKC nanofiber mat presented good biodegradability, adhesiveness, unique mechanical property, expedient water uptake property, sustained drug release, and excellent biocompatibility for chronic wound healing. The in vitro tissue engineering study depicted excellent cell migration and cell-cell interaction in the NIH 3T3 cells over the VKC-impregnated silk fibroin (SF-VKC) mat. A higher population of cell migration was observed in cells' denuded area (scratched region) compared to the native SF fibrous mat. Interestingly, our results demonstrated that the prepared VKC-impregnated SF mat had potentially promoted the STZ-induced diabetic wound healing in a shorter period than the pure SF mat. Thus, obtained in vitro and in vivo outcomes suggest that the VKC-laden SF electrospun fibrous mat could be a better and inexpensive fibrous antibacterial biomaterial to elicit earlier re-epithelialization and efficient matrix remodeling for accelerating chronic infected wound reconstruction in skin diabetic wound healing applications.

Silk fibroin hydrogel as mucosal vaccine carrier: induction of gastric CD4+TRM cells mediated by inflammatory response induces optimal immune protection against Helicobacter felis.

Tissue-resident memory T (TRM) cells, located in the epithelium of most peripheral tissues, constitute the first-line defense against pathogen infections. Our previous study reported that gastric subserous layer (GSL) vaccination induced a "pool" of protective tissue-resident memory CD4+T (CD4+TRM) cells in the gastric epithelium. However, the mechanistic details how CD4+TRM cells form in the gastric epithelium are unknown. Here, our results suggested that the vaccine containing CCF in combination with Silk fibroin hydrogel (SF) broadened the distribution of gastric intraepithelial CD4+TRM cells. It was revealed that the gastric intraepithelial TRM cells were even more important than circulating memory T cells against infection by Helicobacter felis. It was also shown that gastric-infiltrating neutrophils were involved as indispensable mediators which secreted CXCL10 to chemoattract CXCR3+CD4+T cells into the gastric epithelium. Blocking of CXCR3 or neutrophils significantly decreased the number of gastric intraepithelial CD4+TRM cells due to reduced recruitment of CD4+T cells. This study demonstrated the protective efficacy of gastric CD4+TRM cells against H. felis infection, and highlighted the influence of neutrophils on gastric intraepithelial CD4+TRM cells formation.

Silk-coated dexamethasone non-spherical microcrystals for local drug delivery to inner ear.

The local drug delivery systems play an important role in treating sudden sensorineural hearing loss. In this work, we synthesized dexamethasone microcrystals (DEX MCs) using precipitation technique followed by silk coating via layer-by-layer assembly. Compared to raw DEX, the physicochemical properties including shape, crystal form, dispersity, dissolution or sustained release, of DEX MCs or poly-l-lysine/silk fibroin (PLL/SF) multilayers-coated DEX MCs (DEX-(PLL/SF)3) were investigated. More importantly, after a single intratympanic administration in guinea pigs, DEX-(PLL/SF)3 was uniformly distributed on the round window membrane (RWM) in comparison with raw DEX and DEX MCs. And increased concentration of DEX treatment resulted in higher perilymph DEX levels. No significant morphological change and inflammatory responses on the cochlear tissue were observed. Thus, the DEX-(PLL/SF)3 formulation could be a novel local drug delivery strategy to realize safe, efficient and sustainable DEX delivery into inner ear across RWM.

Spidroin in carbopol-based gel promotes wound healing in earthworm's skin model.

Spider silk's regenerative, biocompatible, and antimicrobial properties render it a promising biomaterial for wound healing promotion. Spidroin as the main protein component of spider silks was used in this study to evaluate the potential effects on wound healing via topical application of novel spidroin-containing carbopol 934 (CP934) gel. Spidroin was extracted, formulated into CP934 gel, and characterized both in vitro and in vivo. Spidroin gel was translucent and brownish-yellow in color. An optimum viscosity was obtained at 0.6% CP934 at neutral pH. Optimized spidroin gel (0.6% CP934) effectively inhibited the growth of clinical bacterial isolates of methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA) and Escherichia coli at 440 µg/mL with MIC values of 0.98, 4.6, and 8.2 µg/mL, respectively. Optimized spidroin gel was evaluated for wound healing via topical application on wounds surgically induced in Allolobophora caliginosa earthworms used as a robust human skin model. After application for three consecutive days, dramatic reductions in wound closure and reepithelialization duration were observed macroscopically and via histological studies (light and electron microscopy) when compared with control. In conclusion, these results show that spidroin gel is a promising promoter for wound healing, and further studies would be directed toward investigating mechanisms underlying this effect.

Sustained release silk fibroin discs: Antibody and protein delivery for HIV prevention.

With almost 2 million new HIV infections worldwide each year, the prevention of HIV infection is critical for stopping the pandemic. The only approved form of pre-exposure prophylaxis is a costly daily pill, and it is recognized that several options will be needed to provide protection to the various affected communities around the world. In particular, many at-risk people would benefit from a prevention method that is simple to use and does not require medical intervention or a strict daily regimen. We show that silk fibroin protein can be formulated into insertable discs that encapsulate either an antibody (IgG) or the potent HIV inhibitor 5P12-RANTES. Several formulations were studied, including silk layering, water vapor annealing and methanol treatment to stabilize the protein cargo and impact the release kinetics over weeks. In the case of IgG, high concentrations were released over a short time using methanol treatment, with more sustained results with the use of water vapor annealing and layering during device fabrication. For 5P12-RANTES, sustained release was obtained for 31 days using water vapor annealing. Further, we show that the released inhibitor 5P12-RANTES was functional both in vitro and in ex vivo colorectal tissue. This work shows that silk fibroin discs can be developed into formidable tools to prevent HIV infection.

Silk Fibroin-Coated Nanoagents for Acidic Lysosome Targeting by a Functional Preservation Strategy in Cancer Chemotherapy.

Background: Premature drug leakage and inefficient cellular uptake are stand out as considerable hurdles for low drug delivery efficiency in tumor chemotherapy. Thus, we established a novel drug delivery and transportation strategy mediated by biocompatible silk fibroin (SF)-coated nanoparticles to overcome these therapeutic hurdles. Methods: we first synthesised a TME-responsive biocompatible nanoplatform constructed of amorphous calcium carbonate (ACC) cores and SF shells for enhanced chemotherapy by concurrently inhibiting premature drug release, achieving lysosome-targeted explosion and locally sprayed DOX, and monitoring via PAI, which was verified both in vitro and in vivo. Results: The natural SF polymer first served as a "gatekeeper" to inhibit a drug from prematurely leaking into the circulation was demonstrated both in vitro and in vivo. Upon encountering TMEs and targeting to the acidic pH environments of lysosomes, the sensitive ACC nanoparticles were gradually degraded, eventually generating a large amount of Ca2+ and CO2, resulting in lysosomal collapse, thus preventing both the efflux of DOX from cancer cells and the protonation of DOX within the lysosome, releasing multiple hydrolytic enzyme to cytoplasm, exhibiting the optimal therapeutic dose and remarkable synergetic therapeutic performance. In particular, CO2 gas generated by the pH response of ACC nanocarriers demonstrated their imaging capability for PAI, providing the potential for quantifying and guiding drug release in targets. Conclusion: In this work, we constructed TME-responsive biocompatible NPs by coating DOX-preloaded ACC-DOX clusters with SF via a bioinspired mineralization method for efficient therapeutics. This functional lysosome-targeted preservation-strategy-based therapeutic system could provid novel insights into cancer chemotherapy.

Shape-Dependent Biodistribution of Biocompatible Silk Microcapsules.

Microcapsules are emerging as promising microsize drug carriers due to their remarkable deformability. Shape plays a dominant role in determining their vascular transportation. Herein, we explored the effect of the shape of the microcapsules on the in vivo biodistribution for rational design of microcapsules to achieve optimized targeting efficiency. Silk fibroin, a biocompatible, biodegradable, and abundant material, was utilized as a building block to construct biconcave discoidal and spherical microcapsules with diameter of 1.8 µm and wall thickness of 20 nm. We have compared the cytocompatibility, cellular uptake, and biodistribution of both microcapsules. Both biconcave and spherical microcapsules exhibited excellent cytocompatibility and internalization into cancer cells. During blood circulation in mice, both microcapsules showed retention in liver and kidney and most underwent renal clearance. However, we observed significantly higher accumulation of biconcave silk microcapsules in lung compared with spherical microcapsules, and the accumulation was found to be stable in lung even after 3 days. The higher concentration of biconcave discoidal microcapsules found in lung arises from pulmonary environment, margination dynamics, and enhanced deformation in bloodstream. Red blood cell (RBC)-mimicking silk microcapsules demonstrated here can potentially serve as a promising platform for delivering drugs for lung diseases.

Novel Biodegradable Polymeric Microparticles Facilitate Scarless Wound Healing by Promoting Re-epithelialization and Inhibiting Fibrosis.

Despite decades of research, the goal of achieving scarless wound healing remains elusive. One of the approaches, treatment with polymeric microcarriers, was shown to promote tissue regeneration in various in vitro models of wound healing. The in vivo effects of such an approach are attributed to transferred cells with polymeric microparticles functioning merely as inert scaffolds. We aimed to establish a bioactive biopolymer carrier that would promote would healing and inhibit scar formation in the murine model of deep skin wounds. Here we characterize two candidate types of microparticles based on fibroin/gelatin or spidroin and show that both types increase re-epithelialization rate and inhibit scar formation during skin wound healing. Interestingly, the effects of these microparticles on inflammatory gene expression and cytokine production by macrophages, fibroblasts, and keratinocytes are distinct. Both types of microparticles, as well as their soluble derivatives, fibroin and spidroin, significantly reduced the expression of profibrotic factors Fgf2 and Ctgf in mouse embryonic fibroblasts. However, only fibroin/gelatin microparticles induced transient inflammatory gene expression and cytokine production leading to an influx of inflammatory Ly6C+ myeloid cells to the injection site. The ability of microparticle carriers of equal proregenerative potential to induce inflammatory response may allow their subsequent adaptation to treatment of wounds with different bioburden and fibrotic content.

Immunomodulatory injectable silk hydrogels maintaining functional islets and promoting anti-inflammatory M2 macrophage polarization.

Islet transplantation is considered the most promising treatment for type 1 diabetes. However, the clinical success is limited by islet dysfunction in long-term culture. In this study, we have utilized the rapid self-gelation and injectability offered by blending of mulberry silk (Bombyx mori) with non-mulberry (Antheraea assama) silk, resulting in a biomimetic hydrogel. Unlike the previously reported silk gelation techniques, the differences in amino acid sequences of the two silk varieties result in accelerated gelation without requiring any external stimulus. Gelation study and rheological assessment depicts tuneable gelation as a function of protein concentration and blending ratio with minimum gelation time. In vitro biological results reveal that the blended hydrogels provide an ideal 3D matrix for primary rat islets. Also, A. assama fibroin with inherent Arg-Gly-Asp (RGD) shows significant influence on islet viability, insulin secretion and endothelial cell maintenance. Furthermore, utility of these hydrogels demonstrate sustained release of Interleukin-4 (IL-4) and Dexamethasone with effective M2 macrophage polarization while preserving islet physiology. The immuno-informed hydrogel demonstrates local modulation of inflammatory responses in vivo. Altogether, the results exhibit promising attributes of injectable silk hydrogel and the utility of non-mulberry silk fibroin as an alternative biomaterial for islet encapsulation.

Effect of a Fibroin Enzymatic Hydrolysate on Memory Improvement: A Placebo-Controlled, Double-Blind Study.

The consumption of a specifically prepared silk fibroin protein enzymatic hydrolysate (FPEH) has been reported to improve cognitive function in healthy humans. The objective of the current study is to evaluate the dose-dependent effects of the FPEH on memory. Healthy adults with an average age of approximately 55 years were administered doses of 0, 280, 400 and 600 mg of FPEH per day in two divided doses for 3 weeks. The Rey-Kim Auditory Verbal Learning Test and the Rey-Kim Complex Figure Test of the Rey-Kim Memory Test were used to evaluate memory at baseline and after 3 weeks. The scores for each test were combined into the memory quotient score (MQ). Learning gradient, memory maintenance, retrieval efficacy, and drawing/recall scores were also compared. After 3 weeks of FPEH, dose-dependent increases were observed for the MQ, the learning gradient, the numbers of words remembered, the retrieval efficiency, and drawing/recall. The optimal dose for FPEH was 400 or 600 mg, depending on the end point measured. No adverse effects were reported. FPEH significantly improved measurements of memory in healthy adults by 3 weeks at doses over 280 mg daily, with an apparent plateau effect at 400-600 mg daily.

Partially oxidized polyvinyl alcohol conduitfor peripheral nerve regeneration.

Surgical reconstruction of peripheral nerves injuries with wide substance-loss is still a challenge. Many studies focused on the development of artificial nerve conduits made of synthetic or biological materials but the ideal device has not yet been identified. Here, we manufactured a conduit for peripheral nerve regeneration using a novel biodegradable hydrogel we patented that is oxidized polyvinyl alcohol (OxPVA). Thus, its characteristics were compared with neat polyvinyl alcohol (PVA) and silk-fibroin (SF) conduits, through in vitro and in vivo analysis. Unlike SF, OxPVA and neat PVA scaffolds did not support SH-SY5Y adhesion and proliferation in vitro. After implantation in rat model of sciatic nerve transection, the three conduits sustained the regeneration of the injured nerve filling a gap of 5 mm in 12 weeks. Implanted animals showed a good gait recovery. Morphometric data related to the central portion of the explanted conduit interestingly highlighted a significantly better outcome for OxPVA scaffolds compared to PVA conduits in terms of axon density, also with respect to the autograft group. This study suggests the potential of our novel biomaterial for the development of conduits for clinical use in case of peripheral nerve lesions with substance loss.

Improving glycemic control in model mice with type 2 diabetes by increasing superoxide dismutase (SOD) activity using silk fibroin hydrolysate (SFH).

Islet cell dysfunction in type 2 diabetes is primarily attributed to the increased apoptosis of pancreatic beta cells. Silk fibroin hydrolysate (SFH) has an effect on blood in type 2 diabetes model mice (C57BL/KsJ-db/db). However, its exact mechanism is unknown. The type 2 diabetes model mice were randomly divided into non-diabetic mice (ND), diabetic mice (DB), and diabetic mice treated with silk fibroin hydrolysate (DB-SFH). The results showed that SFH significantly decreased fasting blood glucose and hemoglobin A1c (HbA1c). The oral glucose tolerance and insulin tolerance were significantly improved in the DB-SFH group. The DB-SFH group exhibited increased superoxide dismutase (SOD) activity in the plasma, as well as increased Mn-SOD and CuZn-SOD activities in the pancreatic islets. Furthermore, the pancreatic islet cells' death was decreased in the DB-SFH group. In the DB-SFH group, the protein expression of caspase-3 was significantly decreased compared with the DB group. The expression of the Nkx6.1 and Pdx1 proteins were increased in the DB-SFH group. The results suggest that SFH prevents the degeneration of pancreatic islets via increasing SOD while hyperglycemia is alleviated by maintaining beta cell mass in type 2 diabetes model mice.

Botulinum Toxin Conjugated With Silk Fibroin and 4-Hexylresorcinol.

PURPOSE: The objective of this study was to evaluate whether silk fibroin (SF) incorporated into 4-hexylresorcinol (4HR) could increase botulinum toxin-A (BTX-A) activity. MATERIAL AND METHODS: In total, 30 rats were used for this study. The animals were divided into 6 groups according to the injected materials (SA: saline only; SF; 4HR; B2: 2 units of BTX-A; B2 + SF + 4HR: combination of B2, SF, and 4HR; B5: 5 units of BTX-A). Serial sonography was used for the evaluation of muscle thickness after injection. Immunohistochemical staining was used for the evaluation of myosin type II (myo2) and Bcl-2 protein expression. RESULTS: The relative thickness of the masseter muscle in B2 group was 66.14% ±â€Š4.55% to the preinjection level; in B2 + SF + 4HR group was 54.59% ±â€Š4.83%, and in B5 group was 56.19% ±â€Š8.28%. Any BTX-injected group showed significantly lower value of the relative muscle thickness compared to SA, SF, or 4HR group (P < 0.001 for all). The difference of relative muscle thickness between B2 group and B2 + SF + 4HR group was statistically significant (P < 0.001). The intensity of myo2 immunostaining in B5, B2, and B2 + SF + 4HR group was significantly higher than those in the other groups (P < 0.05). CONCLUSIONS: When 2 units of BTX was incorporated to SF and 4HR, combination formula showed similar activity to those of 5 units of BTX.

Silk fibroin hydrogel as physical barrier for prevention of post hernia adhesion.

BACKGROUND: Adhesion formation remains a major complication following hernia repair surgery. Physical barriers though effective for adhesion prevention in clinical settings are associated with major disadvantages, therefore, needs further investigation. This study evaluates silk fibroin hydrogel as a physical barrier on polypropylene mesh for the prevention of adhesion following ventral hernia repair. STUDY DESIGN: Peritoneal explants were cultured on silk fibroin scaffold to evaluate its support for mesothelial cell growth. Full thickness uniform sized defects were created on the ventral abdominal wall of rabbits, and the defects were covered either with silk hydrogel coated polypropylene mesh or with plain polypropylene mesh as a control. The animals were killed after 1 month, and the adhesion formation was graded; healing response of peritoneum was evaluated by immunohistochemistry with calretinin, collagen staining of peritoneal sections, and expression of PCNA, collagen-I, TNFα, IL6 by real time PCR; and its adverse effect if any was determined. RESULTS: Silk fibroin scaffold showed excellent support for peritoneal cell growth in vitro and the cells expressed calretinin. A remarkable prevention of adhesion formation was observed in the animals implanted with silk hydrogel coated mesh compared to the control group; in these animals peritoneal healing was complete and predominantly by mesothelial cells with minimum fibrotic changes. Expression of inflammatory cytokines decreased compared to control animals, histology of abdominal organs, haematological and blood biochemical parameters remained normal. CONCLUSION: Therefore, silk hydrogel coating of polypropylene mesh can improve peritoneal healing, minimize adhesion formation, is safe and can augment the outcome of hernia surgery.