Comparison of the Effect of Two Hyaluronic Acid Preparations on Fibroblast and Endothelial Cell Functions Related to Angiogenesis

Enzyme variants in biosynthesis and biological assessment of different molecular weight hyaluronan

In the present study, low- and high-molecular-weight hyaluronic acids (LMW-HA and HMW-HA) were synthesized in vitro by truncated Streptococcus equisimilis hyaluronan synthases (SeHAS). The enzyme kinetic parameters were determined for each enzyme variant. The MW, structure, dispersity, and biological activity of polymers were determined by electrophoresis, FTIR spectroscopy, carbazole, cell proliferation, and cell migration assay, respectively. The specific activities were calculated as 7.5, 6.8, 4.9, and 2.8 µgHA µgenzyme-1 min-1 for SeHAS, HAS123, HAS23, and HASIntra, respectively. The results revealed SeHAS produced a polydisperse HMW-HA (268 kDa), while HAS123 and HAS23 produced a polydisperse LMW-HA (< 30 kDa). Interestingly, HASIntra produced a low-disperse LMW-HA. Kinetics studies revealed the truncated variants displayed increased Km values for two substrates when compared to the wild-type enzyme. Biological assessments indicated all LMW-HAs showed a dose-dependent proliferation activity on endothelial cells (ECs), whereas HMW-HAs exhibited an inhibitory effect. Also, LMW-HAs had the highest cell migration effect at 10 µg/mL, while at 200 µg/mL, both LMW- and HMW-HAs postponed the healing recovery rate. The study elucidated that the transmembrane domains (TMDs) of SeHAS affect the enzyme kinetics, HA-titer, HA-size, and HA-dispersity. These findings open new insight into the rational engineering of SeHAS to produce size-defined HA.

Development of propolis, hyaluronic acid, and vitamin K nano-emulsion for the treatment of second-degree burns in albino rats

Burns are the fourth most common type of injury worldwide. Many patients also suffer numerous infections and complications that impair the burn healing process, which makes the treatment of burns a challenge. This study aimed to prepare and characterize nano-emulsion (NE) of propolis, hyaluronic acid, and vitamin K for treatment of second-degree burns. High-Pressure Liquid Chromatography (HPLC) was used for the qualitative assessment of the phenolic and flavonoid contents in crude propolis. The structural, optical, and morphological characterization, besides the antimicrobial, antioxidant, cytotoxicity, in-vitro, and in-vivo wound healing activities were evaluated. For in-vivo study, 30 adult male albino rats were divided randomly into control and treated groups, which were treated with normal saline (0.9%), and NE, respectively. The wounds were examined clinicopathologically on the 3rd, 7th, and 14th days. The NE revealed the formation of a mesh-like structure with a size range of 80-180 nm and a 21.6 ± 6.22 mV zeta potential. The IC50 of NE was 22.29 μg/ml. Also, the NE showed antioxidant and antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The in-vitro investigation of the NE on normal human skin fibroblasts using scratch assay proved an acceleration for wound healing. The treated rats showed improved wound healing clinically and pathologically and wound contraction percent (WC %) was 98.13% at 14th day, also increased epithelization, fibrous tissue formation, collagen deposition, and angiogenesis compared to the control. It could be concluded that the prepared NE possesses antimicrobial, antioxidant, and healing effect in the treatment of second-degree burns.

Molecular weight of hyaluronic acid crosslinked into biomaterial scaffolds affects angiogenic potential

While hyaluronic acid (HA)-based hydrogels have been used clinically for decades, the mechanisms by which HA exerts molecular weight-dependent bioactivity and how chemical modification and crosslinking may affect molecular weight-dependent bioactivity remain poorly understood. This knowledge gap presents a significant barrier to designing HA hydrogels with predictable bioactivities. As HA has been widely reported to have molecular weight-dependent effects on endothelial cells (ECs), we investigated how the molecular weight of HA in either soluble or crosslinked forms affects angiogenesis and interrogated CD44 clustering on the surface of endothelial cells as a candidate mechanism for these affects. Using soluble HA, our results show high molecular weight (HMW) HA, but not low molecular weight (LMW) HA, increased viability and tube formation in cultured human cerebral microvascular ECs (HCMVECs). No size of HA affected proliferation. When HCMVECs were cultured with crosslinked HA of varying molecular weights in the form of HA-based microporous annealed particle scaffold (HMAPS), the cell response was comparable to when cultured with soluble HA. Similarly, when implanted subcutaneously, HMAPS with HMW HA were more vascularized than those with LMW HA. We also show that antibody-mediated CD44 clustering resulted in HCMVECs with increased viability and tube-like structure formation in a manner comparable to exposure to HMW HA, suggesting that HMW acts through CD44 clustering. STATEMENT OF SIGNIFICANCE: Biomaterials based on hyaluronic acid (HA), a bioactive extracellular matrix polysaccharide, have been used in clinical products for several years. Despite the knowledge that HA molecular weight heavily influences its bioactivity, molecular weight has been largely ignored in the development of HA-based biomaterials. Given the high viscosity of high molecular weight HA typically found in native tissues, lower molecular weight polysaccharides have been used most commonly for biomaterial fabrication. By comparing the ability of injectable, microporous annealed particle scaffolds (MAPS) fabricated from variably sized HA to promote angiogenesis, this study demonstrates that MAPS with high molecular weight HA better support vascularization, likely through an unique ability to induce clustering of CD44 receptors on endothelial cells.

In Situ Forming Bioartificial Hydrogels with ROS Scavenging Capability Induced by Gallic Acid Release with Potential in Chronic Skin Wound Treatment

In normal chronic wound healing pathways, the presence of strong and persistent inflammation states characterized by high Reactive Oxygen Species (ROS) concentrations is one of the major concerns hindering tissue regeneration. The administration of different ROS scavengers has been investigated over the years, but their effectiveness has been strongly limited by their short half-life caused by chronic wound environmental conditions. This work aimed at overcoming this criticism by formulating bioartificial hydrogels able to preserve the functionalities of the encapsulated scavenger (i.e., gallic acid-GA) and expand its therapeutic window. To this purpose, an amphiphilic poly(ether urethane) exposing -NH groups (4.5 × 1020 units/gpolymer) was first synthesized and blended with a low molecular weight hyaluronic acid. The role exerted by the solvent on system gelation mechanism and swelling capability was first studied, evidencing superior thermo-responsiveness for formulations prepared in saline solution compared to double demineralized water (ddH2O). Nevertheless, drug-loaded hydrogels were prepared in ddH2O as the best compromise to preserve GA from degradation while retaining gelation potential. GA was released with a controlled and sustained profile up to 48 h and retained its scavenger capability against hydroxyl, superoxide and 1'-diphenyl-2-picrylhydrazyl radicals at each tested time point. Moreover, the same GA amounts were able to significantly reduce intracellular ROS concentration upon oxidative stress induction. Lastly, the system was highly cytocompatible according to ISO regulation and GA-enriched extracts did not induce NIH-3T3 morphology changes.

Anti-Aging and Depigmentation Effect of a Hyaluronic Acid Mechanically Stabilized Complex on Human Skin Explants

Solar radiation and environmental pollutants are factors that cause changes in the skin that trigger skin aging. The objective of the study is to evaluate the rejuvenating effects of a complex formed by hyaluronic acid supplemented with vitamins, amino acids and oligopeptides in explants of human skin. For this, surplus skin samples have been obtained from donors that have been resected and cultivated on slides with membrane inserts. The complex was administered to some skin explants and the percentage of cells with low, medium and high levels of melanin was evaluated as an indicator of the degree of pigmentation. Other skin segments were irradiated with UVA/UVB, then the product was administered on several slides and the levels of collagen, elastin, sulfated GAG and MMP1 were evaluated. The results show that the administration of the complex significantly reduces the percentage of skin cells with a high melanin content by 16%, and that in skin irradiated with UVA/UVB, there is a decrease in the content of collagen, elastin and sulfate GAGs, and the complex reverses this reduction without changing MMP1 levels. This suggests that the compound has anti-aging and depigmentation effects on the skin, giving a skin rejuvenation appearance.

Low molecular weight hyaluronan inhibits lung epithelial ion channels by activating the calcium-sensing receptor

Herein, we tested the hypothesis that low molecular weight hyaluronan (LMW-HA) inhibits lung epithelial ions transport in-vivo, ex-vivo, and in-vitro by activating the calcium-sensing receptor (CaSR). Twenty-four hours post intranasal instillation of 50-150 µg/ml LMW-HA to C57BL/6 mice, there was a 75% inhibition of alveolar fluid clearance (AFC), a threefold increase in the epithelial lining fluid (ELF) depth, and a 20% increase in lung wet/dry (W/D) ratio. Incubation of human and mouse precision cut lung slices with 150 µg/ml LMW-HA reduced the activity and the open probability (Po) of epithelial sodium channel (ENaC) in alveolar epithelial type 2 (ATII) cells, and in mouse tracheal epithelial cells (MTEC) monolayers as early as 4 h. The Cl- current through cystic fibrosis transmembrane conductance regulator (CFTR) and the activity of Na,K-ATPase were both inhibited by more than 66% at 24 h. The inhibitory effects of LMW-HA on ion channels were reversed by 1 µM NPS-2143, or 150 µg/ml high molecular weight hyaluronan (HMW-HA). In HEK-293 cells expressing the calcium-sensitive Cl- channel TMEM16-A, CaSR was required for the activation of the Cl- current by LMW-HA. This is the first demonstration of lung ions and water transport inhibition by LMW-HA, and its mediation through the activation of CaSR.

Application of Stichopus hermanni Nanoparticle Gel in the Healing of Traumatic Ulcers

OBJECTIVE

 The aim of this research was to investigate the use of Stichopus herrmanni nanoparticle gel on the ulcer healing process by observing blood vessels, fibroblasts, and Collagen type-I (COL-1) expression on the 4 and 7th days after trauma.

MATERIALS AND METHODS

 Gold sea cucumber (Stichopus herrmanni) powder was processed by freeze-drying method, then by high-energy milling to form nanoparticle size, and then with CMC 2% to make hydrogel. Traumatic ulcers were formed by induction using a burner. Five groups of male Wistar rats, each consisting of six tails, were divided into a negative control group that was given a placebo, the positive control group was given 0.2% hyaluronic acid, and the treatment group was given gold sea cucumbers with concentrations of 0.135, 0.27, and 0.54% (SH1-SH2-SH3). Fibroblast and blood vessels were examined with hematoxylin-eosin on day 3 and 7, while COL-1 expression was examined with immunohistochemistry on day 7. The rats' mucosa was taken on the 3rd and 7th days after the traumatic ulcer was formed.

STATISTICAL ANALYSIS

 The data were analyzed using a one-way analysis of variance followed by a post-hoc test with a p less than 0.05.

RESULTS

 Nanoparticles gel freeze-drying of Stichopus herrmanni increased blood vessels on day 3. Angiogenesis continued to occur, which resulted in increased fibroblast and COL-1 expression on day 7.

CONCLUSIONS

 The application of Stichopus herrmanni nanoparticle gel at 0.27% effectively increased the number of blood vessels, fibroblasts, and COL-1 expression in healing traumatic ulcers.

The Nitric Oxide Donor [Zn(PipNONO)Cl] Exhibits Antitumor Activity through Inhibition of Epithelial and Endothelial Mesenchymal Transitions

Simple Summary

Nitric oxide (NO) plays a critical pathophysiological role in cancer by modulating several processes, such as angiogenesis, tumor growth, and metastatic potential. The aim of this study was to characterize the antitumor effects of a novel NO donor, [Zn(PipNONO)Cl], on the processes of epithelial– and endothelial–mesenchymal transitions (EMT and EndMT), known to actively participate in cancer progression. Two tumor cells lines were used in this study: human lung cancer cells (A549) and melanoma cells (A375), alone and co-cultured with human endothelial cells. Our results demonstrate that both tumor and endothelial cells were targets of NO action, which impaired EMT and EndMT functional and molecular features. Further studies are needed to finalize the therapeutic use of the novel NO donor.

Abstract

Exogenous nitric oxide appears a promising therapeutic approach to control cancer progression. Previously, a nickel-based nonoate, [Ni(SalPipNONO)], inhibited lung cancer cells, along with impairment of angiogenesis. The Zn(II) containing derivatives [Zn(PipNONO)Cl] exhibited a protective effect on vascular endothelium. Here, we have evaluated the antitumor properties of [Zn(PipNONO)Cl] in human lung cancer (A549) and melanoma (A375) cells. Metastasis initiates with the epithelial–mesenchymal transition (EMT) process, consisting of the acquisition of invasive and migratory properties by tumor cells. At not cytotoxic levels, the nonoate significantly impaired A549 and A375 EMT induced by transforming growth factor-β1 (TGF-β1). Reduction of the mesenchymal marker vimentin, upregulated by TGF-β1, and restoration of the epithelial marker E-cadherin, reduced by TGF-β1, were detected in both tumor cell lines in the presence of Zn-nonoate. Further, the endothelial–mesenchymal transition achieved in a tumor-endothelial cell co-culture was assessed. Endothelial cells co-cultured with A549 or A375 acquired a mesenchymal phenotype with increased vimentin, alpha smooth muscle actin and Smad2/3, and reduced VE-cadherin. The presence of [Zn(PipNONO)Cl] maintained a typical endothelial phenotype. In conclusion, [Zn(PipNONO)Cl] appears a promising therapeutic tool to control tumor growth and metastasis, by acting on both tumor and endothelial cells, reprogramming the cells toward their physiologic phenotypes.

ALDH1A1 overexpression in melanoma cells promotes tumor angiogenesis by activating the IL‑8/Notch signaling cascade

ALDH1A1 is a cytosolic enzyme upregulated in tumor cells, involved in detoxifying cells from reactive aldehydes and in acquiring resistance to chemotherapeutic drugs. Its expression correlates with poor clinical outcomes in a number of cancers, including melanoma. The present study hypothesized that the increased ALDH1A1 expression and activity upregulated the release of proangiogenic factors from melanoma cells, which regulate angiogenic features in endothelial cells (ECs) through a rearrangement of the Notch pathway. In vivo, when subcutaneously implanted in immunodeficient mice, ALDH1A1 overexpressing melanoma cells displayed a higher microvessel density. In a 3D multicellular system, obtained co‑culturing melanoma cancer cells with stromal cells, including ECs, melanoma ALDH1A1 overexpression induced the recruitment of ECs into the core of the tumorspheres. By using a genes array, overexpression of ALDH1A1 in tumor cells also promoted modulation of Notch cascade gene expression in ECs, suggesting an interaction between tumor cells and ECs mediated by enrichment of angiogenic factors in the tumor microenvironment. To confirm this hypothesis, inactivation of ALDH1A1 by the pharmacological inhibitor CM037 significantly affected the release of angiogenic factors, including IL‑8, from melanoma cells. High levels of ALDH1A1, through the retinoic acid pathway, regulated the activation of NF‑kB‑p65 and IL‑8. Further, in a 2D co‑culture system, the addition of an IL‑8 neutralizing antibody to ECs co‑cultured with melanoma cells forced to express ALDH1A1 dampened endothelial angiogenic features, both at the molecular (in terms of gene and protein expression of mediators of the Notch pathway) and at the functional level (proliferation, scratch assay, tube formation and permeability). In conclusion, these findings demonstrated the existence of a link between melanoma ALDH1A1 expression and EC Notch signaling modification that results in a pro‑angiogenic phenotype. Based on the crucial role of ALDH1A1 in melanoma control of the tumor microenvironment, the enzyme seems a promising target for the development of novel drugs able to interrupt the cross‑talk between cancer (stem) cells and endothelial cells.

Characterization of the Safety Profile of Sweet Chestnut Wood Distillate Employed in Agriculture

In organic agriculture, synthetic pesticides and treatments are substituted by natural remedies with interesting success for product yield and environmental outcomes, but the safety of these bio-based products needs to be assessed in vertebrate and human models. Therefore, in this paper we assessed the safety profile of sweet chestnut (Castanea sativa) wood distillate (WD) on the different cellular components of tissues implied in transcutaneous absorption. We investigated the viability of different cell lines mimicking the skin (HaCaT keratinocytes), mucosa (A431), connective (normal human dermal fibroblasts, NHDF) and vascular (human umbilical vein endothelial cells, HUVEC) tissues after exposure to increasing concentrations (0.04–0.5%, v/v, corresponding to 1:2800–1:200 dilutions) of WD. A short exposure to increasing doses of WD was well tolerated up to the highest concentration. Instead, following a prolonged treatment, a concentration dependent cytotoxic effect was observed. Notably, a different behavior was found with the various cell lines, with higher sensitivity to cytotoxicity by the cells with higher proliferation rate and reduced doubling time (human keratinocytes). Moreover, to exclude an inflammatory effect at the not cytotoxic WD concentrations, the expression of the main inducible markers of inflammation, cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1), were assessed, and no improvement was found both after brief and prolonged exposure. In conclusion, our data exclude any inflammatory and cytotoxic effect at the lowest WD concentrations, namely 0.07% and 0.04%, mimicking some recommended dilutions of the product and the potential exposure doses for the operators in agriculture. Nevertheless, higher concentrations showed a safe profile for short time usage, but caution should be used by farmers following persistent product exposure.

Cross-linked hyaluronic acid slows down collagen membrane resorption in diabetic rats through reducing the number of macrophages

OBJECTIVES

We previously showed that accelerated degradation of collagen membranes (CMs) in diabetic rats is associated with increased infiltration of macrophages and blood vessels. Since pre-implantation immersion of CMs in cross-linked high molecular weight hyaluronic acid (CLHA) delays membrane degradation, we evaluated here its effect on the number of macrophages and endothelial cells (ECs) within the CM as a possible mechanism for inhibition of CM resorption.

MATERIALS AND METHODS

Diabetes was induced with streptozotocin in 16 rats, while 16 healthy rats served as control. CM discs were labeled with biotin, soaked in CLHA or PBS, and implanted under the scalp. Fourteen days later, CMs were embedded in paraffin and the number of macrophages and ECs within the CMs was determined using antibodies against CD68 and transglutaminase II, respectively.

RESULTS

Diabetes increased the number of macrophages and ECs within the CMs (∼2.5-fold and fourfold, respectively). Immersion of CMs in CLHA statistically significantly reduced the number of macrophages (p < 0.0001) in diabetic rats, but not that of ECs. In the healthy group, CLHA had no significant effect on the number of either cells. Higher residual collagen area and membrane thickness in CLHA-treated CMs in diabetic animals were significantly correlated with reduced number of macrophages but not ECs.

CONCLUSIONS

Immersion of CM in CLHA inhibits macrophage infiltration and reduces CM degradation in diabetic animals.

CLINICAL RELEVANCE

The combination of CLHA and CM may represent a valuable approach when guided tissue regeneration or guided bone regeneration procedures are performed in diabetic patients.

Integratomics of Human Dermal Fibroblasts Treated with Low Molecular Weight Hyaluronic Acid

Hyaluronic acid (HA) is a glycosaminoglycan very common in commercial products from pharmaceuticals to cosmetics due to its widespread distribution in humans and its diversified physico-chemical proprieties. Despite its extended use and preliminary evidence showing even also opposite activities to the native form, the precise cellular effects of HA at low-molecular-weight (LWM-HA) are currently unclear. The ‘omics sciences currently in development offer a new and combined perspective on the cellular and organismal environment. This work aims to integrate lipidomics analyses to our previous quantitative proteomics one for a multi-omics vision of intra- and extra-cellular impact of different concentrations (0.125, 0.25, and 0.50%) of LMW-HA (20–50 kDa) on normal human dermal fibroblasts by LC-high resolution mass spectrometry (LC-HRMS). Untargeted lipidomics allowed us to identify 903 unique lipids mostly represented by triacylglycerols, ceramides, and phosphatidylcholines. According to proteomics analyses, LMW-HA 0.50% was the most effective concentration also in the lipidome rearrangement especially stimulating the synthesis of ceramides involved in skin hydration and reparation, cell signaling, and energy balance. Finally, integrative analyses showed 25 nodes covering several intra- and extra-cellular functions. The more complete comprehension of intra- and extra-cellular effects of LMW-HA here pointed out will be useful to further exploit its features and improve current formulations even though further studies on lipids biosynthesis and degradation are necessary.

Fabrication, evaluation and applications of dissolving microneedles

In recent years, transdermal preparations have emerged as one of the most promising modes of administration. In particular, dissolving microneedles have attracted extensive attention because of their painlessness, safety, high delivery efficiency and easily operation for patients. This article mainly reviews the preparation methods, the types of matrix polymer materials, the content of dissolving microneedles performance testing, and the applications of dissolving microneedles. It is expected to lay a solid knowledge foundation for the in-depth study of the dissolving microneedles.

Dose- and time-dependent effects of hyaluronidase on structural cells and the extracellular matrix of the skin

Introduction

Hyaluronic acid (hyaluronan; HA) is an essential component of the extracellular matrix (ECM) of the skin. The HA-degrading enzyme hyaluronidase (HYAL) is critically involved in the HA-metabolism. Yet, only little information is available regarding the skin’s HA–HYAL interactions on the molecular and cellular levels.

Objective

To analyze the dose- and time-dependent molecular and cellular effects of HYAL on structural cells and the HA-metabolism in the skin.

Materials and methods

Chip-based, genome-wide expression analyses (Affymetrix® GeneChip PrimeView™ Human Gene Expression Array), quantitative real-time PCR analyses, enzyme-linked immunosorbent assay (ELISA), immunohistochemistry (DAB), and in vitro wound healing assays were performed to assess dose-dependent and time-kinetic effects of HA and HYAL (bovine hyaluronidase, Hylase “Dessau”) on normal human dermal fibroblasts (NHDF), primary human keratinocytes in vitro and human skin samples ex vivo.

Results

Genome-wide expression analyses revealed an upregulation of HA synthases (HAS) up to 1.8-fold change in HA- and HYAL-treated NHDF. HA and HYAL significantly accelerated wound closure in an in vitro model for cutaneous wound healing. HYAL induced HAS1 and HAS2 mRNA gene expression in NHDF. Interestingly, low concentrations of HYAL (0.015 U/ml) resulted in a significantly higher induction of HAS compared to moderate (0.15 and 1.5 U/ml) and high concentrations (15 U/ml) of HYAL. This observation corresponded to increased concentrations of HA measured by ELISA in conditioned supernatants of HYAL-treated NHDF with the highest concentrations observed for 0.015 U/ml of HYAL. Finally, immunohistochemical analysis of human skin samples incubated with HYAL for up to 48 h ex vivo demonstrated that low concentrations of HYAL (0.015 U/ml) led to a pronounced accumulation of HA, whereas high concentrations of HYAL (15 U/ml) reduced dermal HA-levels.

Conclusion

HYAL is a bioactive enzyme that exerts multiple effects on the HA-metabolism as well as on the structural cells of the skin. Our results indicate that HYAL promotes wound healing and exerts a dose-dependent induction of HA-synthesis in structural cells of the skin. Herein, interestingly the most significant induction of HAS and HA were observed for the lowest concentration of HYAL.

Hyaluronic acid as a bioactive component for bone tissue regeneration: Fabrication, modification, properties, and biological functions

Hyaluronic acid (HA) is widely distributed in the human body, and it is heavily involved in many physiological functions such as tissue hydration, wound repair, and cell migration. In recent years, HA and its derivatives have been widely used as advanced bioactive polymers for bone regeneration. Many medical products containing HA have been developed because this natural polymer has been proven to be nontoxic, noninflammatory, biodegradable, and biocompatible. Moreover, HA-based composite scaffolds have shown good potential for promoting osteogenesis and mineralization. Recently, many HA-based biomaterials have been fabricated for bone regeneration by combining with electrospinning and 3D printing technology. In this review, the polymer structures, processing, properties, and applications in bone tissue engineering are summarized. The challenges and prospects of HA polymers are also discussed.

Biochemical characterization of Nostoc sp. exopolysaccharides and evaluation of potential use in wound healing

Exopolysaccharides (EPS) produced by cyanobacteria are complex biomolecules of anionic nature with potential biomedical applications. In this study, the EPS produced by the Nostoc sp. strains PCC7936 and PCC7413 were characterized and evaluated as a biomaterial for new wound dressings. The addition of acetate ions to the culture medium slightly stimulated EPS production, achieving 1463.1 ± 16.0 mgL^-1 (PCC7413) and 1372.1 ± 29.0 mgL^-1 (PCC7936). Both EPS presented nine monosaccharide residues and a MW > 1000 kDa. The acetate addition changed the monosaccharide molar percentages. FTIR and DLS results confirmed the anionic nature and the presence of sulfate groups in both EPS, which are determinant features for biomedical applications. Both EPS at 1%(w/v) formed gels in the presence of 0.4%(w/v) FeCl₃. Results obtained for MTT assay and wound healing in vitro scratch assay revealed hydrogels biocompatibility and ability to promote fibroblast migration and proliferation that was greater in PCC7936. The Nostoc EPS hydrogels presented promising properties to be applied in the treatment of skin injuries.

A Novel Composite Hydrogel Composed of Formic Acid-Decellularized Pepsin-Soluble Extracellular Matrix Hydrogel and Sacchachitin Hydrogel as Wound Dressing to Synergistically Accelerate Diabetic Wound Healing

Extracellular matrix (ECM) hydrogel can create a favorable regenerative microenvironment and act as a promising dressing for accelerating the healing of diabetic wound. In this study, a simple and effective decellularization technique was developed and optimized to obtain acellular extracellular matrix (aECM) from porcine skin. It was found that decellularization at 30% formic acid for 72 h effectively decellularized porcine skin while retaining >75% collagen and ~37% GAG in the aECM with no presence of nuclei of cellular remnants. aECM hydrogel was fabricated by digesting aECM with pepsin in various acidic solutions (0.1 N HCl, glycolic acid (GA) and 2-pyrrolidone-5-carboxylic acid (PCA)) and then treated with a pH-controlled neutralization and temperature-controlled gelation procedure. Based on physical characterizations, including SDS-PAGE, rheological analysis and SEM analysis, aECM_HCl hydrogels fabricated at 25 mg/mL in 0.1 N HCl were selected. Four polymeric ECM-mimic hydrogels, including sacchachitin (SC), hyaluronic acid (HA) and chitosan (CS) and three composite hydrogels of combining SC either with aECM_HCl,25 (aECM_HCl/SC), HA (HA/SC) or CS (SC/CS) were prepared and evaluated for WS-1 cell viability and wound-healing effectiveness. Cell viability study confirmed that no hydrogel dressings possessed any toxicity at all concentrations examined and ECM_HCl, HA and ECM_HCl/SC at higher concentrations (>0.05%) induced statistically significant proliferation. Diabetic wound healing study and histological examinations revealed that ECM_HCl/SC hydrogel was observed to synergistically accelerate wound healing and ultimately stimulated the growth of hair follicles and sweat glands in the healing wound indicating the wound had healed as functional tissues. The results support the great potential of this newly produced ECM_HCl/SC composite hydrogel for healing and regeneration of diabetic wounds.