Hydrogel Group Research Articles

Preparation of Ultra-Small Copper Nanoparticles-Loaded Self-Healing Hydrogels with Antibacterial, Inflammation-Suppressing and Angiogenesis-Enhancing Properties for Promoting Diabetic Wound Healing.

Bacterial invasion, protracted inflammation, and angiogenesis inhibition are hallmarks of chronic diabetic wounds, bringing about patient morbidity and rising healthcare costs. For such wounds, there are currently few efficient therapies available. We reported the development of carboxymethyl chitosan (CMCS)-based self-healing hydrogel loaded with ultra-small copper nanoparticles (Cunps) for local treatment of diabetic wound healing. The structure of Cunps was identified by XRD, TEM, XPS and other methods, and the characterization of the synthesized Cunps-loaded self-healing carboxymethyl chitosan (CMCS)-protocatechualdehyde (PCA) hydrogel (Cunps@CMCS-PCA hydrogel) was further investigated. The therapeutic effect of Cunps@CMCS-PCA hydrogel in diabetic wound healing was explored in vitro and in vivo. The findings showed that a kind of ultra-small size copper nanoparticles with excellent biocompatibility was prepared. CMCS was chemically conjugated to PCA to form self-healing hydrogels via the formation of an amide bond followed by the loading of ultra-small copper nanoparticles. The obtained Cunps@CMCS-PCA hydrogel showed a typical three-dimensional interlinked network structure with self-healing ability and porosity. It exhibited good biocompatibility in diabetic wounds. Furthermore, Cunps@CMCS-PCA hydrogel group significantly prevented bacterial growth in the skin wound of diabetic rats as compared to model group and CMCS-PCA hydrogel-treated group. After 3 days, no visible bacterial proliferation was observed. It also increased angiogenesis through Cunps mediated activation of ATP7A to prevent induction of autophagy. Furthermore, Cunps@CMCS-PCA hydrogel mainly depended on PCA-induced inhibition on inflammation of macrophage via JAK2/STAT3 signaling pathway. As a result, compared with delayed wound healing process with lower wound healing rate valued at 68.6% within 7 days in the model group, Cunps@CMCS-PCA significantly accelerated wound healing recovery and increased wound healing rate to 86.5%, suggesting that Cunps@CMCS-PCA hydrogel effectively accelerated wound healing. Cunps@CMCS-PCA hydrogel offered a new therapeutic approach for quickening diabetic wound healing.

Morphological Effect on Swelling Behaviour of Carboxymethyl Cellulose–Maleic Acid Hydrogel Modified with Kombucha Bacterial Cellulose

The incorporation of bacterial cellulose from kombucha tea in carboxymethyl cellulose / maleic acid (CMC / MA) hydrogels has been successfully conducted. This study aims to analyze the relationship between the pores on the surface of the hydrogel with their water-absorbing ability. Bacterial cellulose from kombucha (KBC) was confirmed by the spectrum of OH, C-O-C, and C-OH functional groups with FT - IR analysis. Filler KBC was added to CMC / MA hydrogel with variations in the concentration of 2, 4, 6, and 8 % wt. The CMC / MA / KBC hydrogels were characterized by swelling test, degree of crosslinking, FTIR, and SEM. The swelling results showed that hydrogels with 2 % KBC produced the best water absorbing ability up to 172 %, water absorption decreased with the increase of KBC concentrations. Furthermore, SEM image results showed that the addition of KBC affects the morphological shape and pore size of the hydrogel. Meanwhile, FTIR analysis showed that there were no major changes in the functional groups of hydrogels.

Treating colorectal peritoneal metastases with an injectable cytostatic loaded supramolecular hydrogel in a rodent animal model

Patients with peritoneal metastases (PM) of colorectal cancer have a very poor outcome. Intraperitoneal delivery of chemotherapy is the preferred route for PM treatment. The main limitation of the treatment options is the short residence time of the cytostatic, with subsequent short exposure of the cancer cells. To address this, a supramolecular hydrogel has been developed that allows both local and slow release of its encapsulated drug, mitomycin C (MMC) or cholesterol-conjugated MMC (cMMC), respectively. This experimental study investigates if drug delivery using this hydrogel improves the therapeutic efficacy against PM. PM was induced in WAG/Rij rats (n = 72) by intraperitoneally injecting syngeneic colon carcinoma cells (CC531) expressing luciferase. After seven days, animals received a single intraperitoneal injection with saline (n = 8), unloaded hydrogel (n = 12), free MMC (n = 13), free cMMC (n = 13), MMC-loaded hydrogel (n = 13), or cMMC-loaded hydrogel (n = 13). Primary outcome was overall survival with a maximum follow-up of 120 days. Intraperitoneal tumor development was non-invasive monitored via bioluminescence imaging. Sixty-one rats successfully underwent all study procedures and were included to assess therapeutic efficacy. After 120 days, the overall survival in the MMC-loaded hydrogel and free MMC group was 78% and 38%, respectively. A trend toward significance was found when comparing the survival curves of the MMC-loaded hydrogel and free MMC (p = 0.087). No survival benefit was found for the cMMC-loaded hydrogel compared to free cMMC. Treating PM with our MMC-loaded hydrogel, exhibiting prolonged MMC exposure, seems effective in improving survival compared to treatment with free MMC.

47. Flowable Decellularized Dermal Hydrogel Improves Integration of Acellular Dermal Matrices

PURPOSE: Acellular dermal matrices (ADM) have revolutionized pre-pectoral implant-based breast reconstruction allowing for improved pocket control and more rapid expansion but with the drawback of an increased risk of seroma that can lead to major complications including implant loss. The majority of these complications are a result of delayed or insufficient wound healing and integration of the ADM. ADM bio-integration can be accelerated by increasing the surface area of the ADM:host soft tissue interface. To address the issue of persistent contact of the ADM with the patient, we investigated the application of a hydrogel, derived from ADM to increase the conduction of the cells and molecular signals and increase vascularization, is critical to biointegration. METHODS: C57bl/6 mice received bilateral subcutaneous pockets. A 5mm diameter ADM implant was placed into each pocket and into one, 0.5 mL of decellularized dermal hydrogel was injected. Implants were harvested at terminal endpoints at 1, 3, and 6 weeks. Flow cytometry was performed to assess a panel of 12 macrophage markers (pan-, M1, M2, or transition) to evaluate inflammatory effects. Immunohistochemical staining for vimentin was used to assess fibroblast migration into the ADM. Hematoxylin and eosin (H&E) staining of implant cross sections was performed for pathological analysis of fibrosis via capsule formation. Capsule thickness, cellularity, foreign bodies, and smooth muscle actin (SMA) were graded (0 = none, 1 = mild, 2 = moderate, 3 = severe). RESULTS: H&E staining demonstrated that the dermal hydrogel persisted adjacent to the ADM implant. Flow cytometry results demonstrated that DPD hydrogel and ADM did not elicit an increased macrophage response compared to ADM implants alone. Vimentin expression demonstrated an upward trend in fibroblast infiltration from 3 to 6, with the dermal hydrogel group fibroblast increase outpacing that of the ADM control. Pathological analysis showed minimal capsule formation and no significant increase in fibrosis between hydrogel and no hydrogel groups. CONCLUSIONS: Our dermal hydrogel was able to flow easily into the surgical pocket, polymerized at physiological temperatures, and remained in place over the course of 6 weeks, demonstrating its potential to bridge the gap between ADM and the overlying skin envelope within human breast reconstructions. Our murine model revealed that the dermal hydrogel did not lead to an increased inflammatory immune response, with no statistical difference in fibrosis scores between t ADM-only implants. Although not statistically significant, immunohistochemistry quantifying the amount of vimentin present in the hydrogel-ADM complex showed promising trends with ADM integration into host tissue. Future work will include expansion of the model to incorporate radiation in order to examine the ability of the dermal hydrogel to aid in wound healing and ADM integration within an environment mirroring that seen in irradiated mastectomy cases.

An Adhesive/Anti-Adhesive Janus Tissue Patch for Efficient Closure of Bleeding Tissue with Inhibited Postoperative Adhesion.

Most of the current bioadhesives cannot perform well on bleeding tissues while postoperative adhesion is a general but serious clinical issue. Here, a three-layer biodegradable Janus tissue patch (J-TP) that is able to simultaneously enable efficient closure of bleeding wounds with significantly promoted clotting ability and suppressed postoperative adhesion of tissues is reported. A dry adhesive hydrogel bottom layer of the J-TP can form rapid (within 15 s) and strong (tensile strength up to 98kPa) adhesion to bleeding/wet tissues with high bursting pressure (about 312.5mmHg on a sealed porcine skin) through hydrogen binding and covalent conjugation between the carboxyl & N-hydroxy succinimide (NHS) groups of hydrogel and the primary amine groups of tissues, while the phosphonic motifs can significantly reduce blood loss (by 81% on a rat bleeding liver model) of bleeding wounds. A thin polylactic acid (PLA) middle layer can improve the tensile strength (by 132%) of the J-TP in wet conditions while the grafted zwitterionic polymers can effectively prevent postoperative tissue adhesion and inflammatory reaction. This J-TP may be a promising tissue patch to assist the clinical treatment of injured bleeding tissues with inhibited postoperative adhesion.

MP01-03 XENO-FREE PEPTIDE-FUNCTIONALIZED BIOINKS IMPROVE EX VIVO CULTURE OF HUMAN TESTICULAR TISSUES

You have accessJournal of UrologyCME1 Apr 2023MP01-03 XENO-FREE PEPTIDE-FUNCTIONALIZED BIOINKS IMPROVE EX VIVO CULTURE OF HUMAN TESTICULAR TISSUES Meghan Robinson and Ryan Flannigan Meghan RobinsonMeghan Robinson More articles by this author and Ryan FlanniganRyan Flannigan More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003212.03AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The development of human in vitro spermatogenesis (IVS) is a promising regenerative platform for the treatment of male factor infertility. IVS has been demonstrated in rodent models, but despite decades of research remains a challenge in the human sphere. A promising strategy may be to culture fragments of testis tissues in hydrogels. Hydrogels can be functionalized to sequester matrix and signaling peptides in a local manner mimicking tissue niche function. In this study we investigated the use of xeno-free hydrogels functionalized with biomimetic peptide motifs for their ability to improve ex vivo culture of human testicular tissues. METHODS: Human testicular tissues were obtained from hormone-treated gender affirmation patients following informed consent, gently teased apart, cut into small fragments and mixed into bioinks (VitroInk) containing either YIGSR (laminin), COL (collagen), or MMPs (matrix metalloproteinases) peptide motifs, then printed into ∼1 cm3 droplets using a BioX6 extrusion bioprinter (Figure 1A). 1 mL of media was placed on each and they were cultured in 34°C at 5% CO2 and ambient oxygen (21%) for 12 days, with 50% media changes every other day. The media consisted of Human Plasma-Like Medium (HPLM) with 15% CTS™ KnockOut™ SR XenoFree Medium, vitamins, metabolites, antioxidants, growth factors and hormones known to be present in the testis niche. Tissues were analyzed after 12 days by quantitative real-time polymerase chain reaction (qPCR) for gene expression associated with apoptosis, somatic cell function, spermatogonial stem cell maintenance, and spermatogenesis. RESULTS: After 12 days gene expression associated with somatic cell function and spermatogenesis was higher than suspension culture controls in all hydrogel groups (Figure 1B). Compared to freshly harvested testicular tissues, COL- and YIGSR-functionalized hydrogels exhibited similar expression levels of genes associated with somatic cell function, and the highest increased levels of genes associated with early spermatogenesis (Figure 1B). CONCLUSIONS: COL- or YIGSR peptide-functionalized hydrogels sustain testicular tissue function ex vivo in short-term cultures, whereas suspension culture exhibited tissue function loss, suggesting the utility of functionalized hydrogels for human IVS. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e1 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Meghan Robinson More articles by this author Ryan Flannigan More articles by this author Expand All Advertisement PDF downloadLoading ...

In vitro evaluation of genipin-crosslinked gelatin hydrogels for vocal fold injection

Glottic insufficiency is one of the voice disorders affecting all demographics. Due to the incomplete closure of the vocal fold, there is a risk of aspiration and ineffective phonation. Current treatments for glottic insufficiency include nerve repair, reinnervation, implantation and injection laryngoplasty. Injection laryngoplasty is favored among these techniques due to its cost-effectiveness and efficiency. However, research into developing an effective injectable for the treatment of glottic insufficiency is currently lacking. Therefore, this study aims to develop an injectable gelatin (G) hydrogel crosslinked with either 1-ethyl-3-(3-dimethylaminpropyl)carbodiimide hydrochloride) (EDC) or genipin (gn). The gelation time, biodegradability and swelling ratio of hydrogels with varying concentrations of gelatin (6–10% G) and genipin (0.1–0.5% gn) were investigated. Some selected formulations were proceeded with rheology, pore size, chemical analysis and in vitro cellular activity of Wharton's Jelly Mesenchymal Stem Cells (WJMSCs), to determine the safety application of the selected hydrogels, for future cell delivery prospect. 6G 0.4gn and 8G 0.4gn were the only hydrogel groups capable of achieving complete gelation within 20 min, exhibiting an elastic modulus between 2 and 10 kPa and a pore size between 100 and 400 μm. Moreover, these hydrogels were biodegradable and biocompatible with WJMSCs, as > 70% viability were observed after 7 days of in vitro culture. Our results suggested 6G 0.4gn and 8G 0.4gn hydrogels as potential cell encapsulation injectates. In light of these findings, future research should focus on characterizing their encapsulation efficiency and exploring the possibility of using these hydrogels as a drug delivery system for vocal fold treatment.

Role of Berberine Thermosensitive Hydrogel in Periodontitis via PI3K/AKT Pathway In Vitro.

Periodontitis is a long-term inflammatory illness and a leading contributor to tooth loss in humans. Due to the influence of the anatomic parameters of teeth, such as root bifurcation lesions and the depth of the periodontal pocket, basic periodontal treatment on its own often does not completely obliterate flora microorganisms. As a consequence, topical medication has become a significant supplement in the treatment of chronic periodontitis. Berberine (BBR) has various pharmacological effects, such as hypoglycemic, antitumor, antiarrhythmic, anti-inflammatory, etc. The target of our project is to develop a safe and non-toxic carrier that can effectively release berberine, which can significantly reduce periodontal tissue inflammation, and to investigate whether berberine thermosensitive hydrogel can exert anti-inflammatory and osteogenic effects by modulating phosphatifylinositol-3-kinase/Protein Kinase B (PI3K/AKT) signaling pathway. Consequently, firstly berberine temperature-sensitive hydrogel was prepared, and its characterizations showed that the mixed solution gelated within 3 min under 37 °C with a hole diameter of 10-130 µm, and the accumulation of berberine release amounted to 89.99% at 21 days. CCK-8 and live-dead cell staining results indicated that this hydrogel was not biotoxic, and it is also presumed that the optimum concentration of berberine is 5 µM, which was selected for subsequent experiments. Real-time polymerase chain reaction (qRT-PCR) and Western blotting (WB)results demonstrated that inflammatory factors, as well as protein levels, were significantly reduced in the berberine-loaded hydrogel group, and LY294002 (PI3K inhibitor) could enhance this effect (p < 0.05). In the berberine-loaded hydrogel group, osteogenesis-related factor levels and protein profiles were visibly increased, along with an increase in alkaline phosphatase expression, which was inhibited by LY294002 (p < 0.05). Therefore, berberine thermosensitive hydrogel may be an effective treatment for periodontitis, and it may exert anti-inflammatory and osteogenic effects through the PI3K/AKT signaling pathway.

Potential of an Aligned Porous Hydrogel Scaffold Combined with Periodontal Ligament Stem Cells or Gingival Mesenchymal Stem Cells to Promote Tissue Regeneration in Rat Periodontal Defects.

Periodontal tissue regeneration is a major challenge in tissue engineering due to its regenerated environment complexity. It aims to regenerate not only the supporting alveolar bone and cementum around teeth but also the key connecting periodontal ligament. Herein, a constructed aligned porous hydrogel scaffold carrying cells based on chitosan (CHI) and oxidized chondroitin sulfate (OCS) treated with a freeze-casting technique was fabricated, which aimed to induce the arrangement of periodontal tissue regeneration. The microscopic morphology and physical and chemical properties of the hydrogel scaffold were evaluated. The biocompatibilities with periodontal ligament stem cells (PDLSCs) or gingival-derived mesenchymal stem cells (GMSCs) were verified, respectively, by Live/Dead staining and CCK8 in vitro. Furthermore, the regeneration effect of the aligned porous hydrogel scaffold combined with PDLSCs and GMSCs was evaluated in vivo. The biocompatibility experiments showed no statistical significance between the hydrogel culture group and blank control (P > 0.05). In a rat periodontal defect model, PDLSC and GMSC hydrogel experimental groups showed more pronounced bone tissue repair than the blank control (P < 0.05) in micro-CT. In addition, there was more tissue repair (P < 0.05) of PDLSC and GMSC hydrogel groups from histological staining images. Higher expressions of OPN, Runx-2, and COL-I were detected in both of the above groups via immunohistochemistry staining. More importantly, the group with the aligned porous hydrogel induced more order periodontal ligament formation than that with the ordinary hydrogel in Masson's trichrome analysis. Collectively, it is expected to promote periodontal tissue regeneration utilizing an aligned porous hydrogel scaffold combined with PDLSCs and GMSCs (CHI-OCS-PDLSC/GMSC composite), which provides an alternative possibility for clinical application.

Human umbilical cord blood mononuclear cells laden hydrogels made from carboxymethyl chitosan and oxidized hyaluronic acid for wound healing

AbstractA dynamic hydrogel was prepared from N,O‐carboxymethyl chitosan (NOCC) and oxidized aldehyde‐containing hyaluronic acid (A‐HA) by Schiff base reaction. The resulted NOCC/A‐HA hydrogels were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). The rheological, swelling, and self‐healing properties of hydrogels were determined. The hydrogels present interconnected porous structure, high swelling rate, and outstanding self‐healing capacity. The biocompatibility of hydrogels was evidenced by MTT assay and zebrafish embryonic toxicity test. Human umbilical cord blood mononuclear cells (CB‐MNC) were encapsulated in the hydrogel. High cell viability above 50% was obtained after 21 days culture. A mouse scald model was realized to evaluate the potential of cell laden hydrogel in wound healing. Compared to the control group and the hydrogel group, the cell laden hydrogel group exhibits faster epidermal regeneration, reduced inflammation and more neovascularization. Therefore, NOCC/A‐HA hydrogels encapsulating CB‐MNC could be a promising therapy in the treatment of burns or scalds.

In vitro complete differentiation of human spermatogonial stem cells to morphologic spermatozoa using a hybrid hydrogel of agarose and laminin

Spermatogenesis refers to the differentiation of the spermatogonial stem cells (SSCs) located in the base seminiferous tubules into haploid spermatozoa. Prerequisites for in vitro spermatogenesis include an extracellular matrix (ECM), paracrine factors, and testicular somatic cells which play a supporting role for SSCs. Thus, the present study evaluated the potential of co-culturing Sertoli cells and SSCs embedded in a hybrid hydrogel of agarose and laminin, the main components of the ECM. Following the three–week conventional culture of human testicular cells, the cells were cultured in agarose hydrogel or agarose/laminin one (hybrid) for 74 days. Then, immunocytochemistry, real-time PCR, electron microscopy, and morphological staining methods were applied to analyze the presence of SSCs, as well as the other cells of the different stages of spermatogenesis. Based on the results, the colonies with positive spermatogenesis markers were observed in both culture systems. The existence of the cells of all three phases of spermatogenesis (spermatogonia, meiosis, and spermiogenesis) was confirmed in the two groups, while morphological spermatozoa were detected only in the hybrid hydrogel group. Finally, a biologically improved 3D matrix can support all the physiological activities of SSCs such as survival, proliferation, and differentiation.

Intervertebral disk regeneration in a rat model by allopurinol-loaded chitosan/alginate hydrogel.

Intervertebral disk degeneration remains one of the most challenging health problems. In the current study, allopurinol was loaded into the chitosan nanoparticles and then incorporated into chitosan/alginate hydrogels and then further studied for its disk regeneration potential in a rat model. In vitro studies were performed to characterize the hydrogel system, including scanning electron microscopy, cell viability assay, cytoprotection assay, cell migration assay, swelling assay, and drug release assay. In vivo study was performed in a rat model of the intervertebral disk injury. Animal studies showed that allopurinol-loaded hydrogels had significantly higher disk regeneration potential compared with other experimental groups. The gene expression studies showed that the animals treated with allopurinol-loaded hydrogel had significantly higher tissue expression levels of type I and type II collagen genes than other groups. Furthermore, the tissue expression levels of nuclear factor κB (NF-κB) and glutathione peroxidase (GPx) genes were significantly lower in this group. The relative expression levels of type I collagen, type II collagen, NF-κB, and GPx genes in the allopurinol-loaded hydrogel group were 2.77 ± 0.2%, 2.86 ± 0.25%, 0.58 ± 0.03%, and 0.45 ± 0.02%, respectively. We showed for the first time that allopurinol-loaded hydrogel promoted intervertebral disk repair, which could be due to its potential to modulate oxidative stress, reduce inflammation, and improve matrix synthesis.

Basic fibroblast growth factor/chitosan derivatives/collagen composite thermosensitive hydrogel promotes perio-dontal tissue regeneration in rats.

To investigate the feasibility of different thermosensitive composite hydrogels from chitosan derivatives as scaffold materials for periodontal tissue engineering. Three chitosan derivatives with different biological characteristics were prepared, namely, sulfonated chitosan (SCS), phosphorylated chitosan (PCS), and phosphorylated sulfonated chitosan (PSCS). Three thermosensitive composite hydrogels were constructed using basic fibroblast growth factor (bFGF), the chitosan derivatives, and collagen. Twenty male Wistar rats were randomly divided into control group, blank group, bFGF/SCS/collagen composite thermosensitive hydrogel group, bFGF/PCS/collagen compo-site thermosensitive hydrogel group, and bFGF/PSCS/collagen composite thermosensitive hydrogel group. Then, three-wall intrabony defects were established. The defects were treated with the different kinds of thermosensitive composite hydrogels. After 6 weeks of surgery, the animals were killed, and specimens were collected. Then, gross observation, hematoxylin-eosin staining, and Masson staining were performed. The bFGF/chitosan derivatives/collagen composite thermosensitive hydrogel groups and the control group had statistical differences in the relative alveolar bone height, relative epithelial down growth and grading count score of periodontal tissue regeneration (P<0.05). bFGF/chitosan derivatives/collagen composite thermosensitive hydrogels have good application prospects in periodontal tissue engineering.

A Dual-Crosslinked Hydrogel Based on Gelatin Methacryloyl and Sulfhydrylated Chitosan for Promoting Wound Healing.

The skin is the largest organ of the human body. Skin injuries, especially full-thickness injuries, are a major treatment challenge in clinical practice. Therefore, wound dressing materials with therapeutic effects have great practical significance in healthcare. This study used photocrosslinkable gelatin methacryloyl (GelMA) and sulfhydrylated chitosan (CS-SH) to design a double-crosslinked hydrogel for wound dressing. When crosslinked together, the resulting hydrogels showed a highly porous inner structure, and enhanced mechanical properties and moisture retention capacity. The compression modulus of the GelMA/CS-SH hydrogel (GCH) reached up to about 40 kPa and was much higher than that of pure GelMA hydrogel, and the compression modulus was increased with the amount of CS-SH. In vitro study showed no cytotoxicity of obtained hydrogels. Interestingly, a higher concentration of CS-SH slightly promoted the proliferation of cells. Moreover, the double-crosslinked hydrogel exhibited antibacterial properties because of the presence of chitosan. In vivo study based on rats showed that full-thickness skin defects healed on the 15th day. Histological results indicate that the hydrogel accelerated the repair of hair follicles and encouraged the orderly growth of collagen fibers in the wound. Furthermore, better blood vessel formation and a higher expression of VEGFR were observed in the hydrogel group when compared with the untreated control group. Based on our findings, GCH could be a promising candidate for full-thickness wound dressing.

Experimental study on the repair of spinal cord injury by conducting hydrogel loaded with tetramethylpyrazine sustained-release microparticles

To investigate the neuroprotective effect of conducting hydrogel loaded with tetramethylpyrazine sustained-release microparticles (hereinafter referred to as "TGTP hydrogel") on spinal cord injury rats. Forty-eight adult female Sprague Dawley rats were randomly divided into 4 groups: sham operation group (group A), model group (group B), conductive hydrogel group (group C), and TGTP hydrogel group (group D), with 12 rats in each group. Only laminectomy was performed in group A, and complete spinal cord transection was performed in groups B, C, and D. Basso-Bettie-Bresnahan (BBB) score was used to evaluate the recovery of hind limb motor function of each group before modeling and at 1, 3, 7, 14, and 28 days after modeling, respectively. At 28 days after modeling, the rats were sacrificed for luxol fast blue (LFB) staining to detect myelin regeneration. Nissl staining was used to detect the survival of neurons. Immunohistochemical staining was used to evaluate the expression of inflammation-related factors [nuclear factor кB (NF-кB), tumor necrosis factor α (TNF-α), and interleukin 10 (IL-10)]. Immunofluorescence staining and Western blot were used to evaluate the expression of neurofilament 200 (NF200). BBB scores of group A were significantly better than those of the other three groups at all time points after modeling (P<0.05); at 14 and 28 days after modeling, there was no significant difference in BBB scores between groups C and D (P>0.05), but the BBB score of group D was significantly better than that of group B (P<0.05). LFB staining and Nissl staining showed that the structure of neurons and myelin in group A was intact, and the myelin integrity and survival number of neurons in group D were significantly better than those in groups B and C. Immunohistochemical staining showed that the absorbency (A) value of NF-кB and TNF-α in group A were significantly lower than those in groups B and C (P<0.05), the A value of IL-10 was significantly higher than that in the other three groups (P<0.05); the A value of NF-κB in group D was significantly lower than that in groups B and C, the A value of TNF-α in group D was significantly lower than that in group B, while the A value of IL-10 in group D was significantly higher than that in group B (P<0.05). Immunofluorescence staining showed that the structure of neurons and nerve fibers in group A was clear and the fluorescence intensity was high. The fluorescence intensity of NF200 in group D was higher than that in groups B and C, and some nerve fibers could be seen. Western blot analysis showed that the relative expression of NF200 in group A was the highest, and the relative expression of NF200 in group D was significantly higher than that in groups B and C (P<0.05). The TGTP hydrogel can effectively promote the recovery of motor function in rats with spinal cord injury, and its mechanism may be related to the regulation of inflammatory response.

BMSCs-Seeded Interpenetrating Network GelMA/SF Composite Hydrogel for Articular Cartilage Repair.

Because of limited self-healing ability, the treatment of articular cartilage defects is still an important clinical challenge. Hydrogel-based biomaterials have broad application prospects in articular cartilage repair. In this study, gelatin methacrylate (GelMA)and silk fibroin (SF) were combined to form a composite hydrogel with an interpenetrating network (IPN) structure under ultraviolet irradiation and ethanol treatment. Introducing silk fibroin into GelMA hydrogel significantly increased mechanical strength as compressive modulus reached 300 kPa in a GelMA/SF-5 (50 mg/mL silk fibroin) group. Moreover, composite IPN hydrogels demonstrated reduced swelling ratios and favorable biocompatibility and supported chondrogenesis of bone mesenchymal stem cells (BMSCs) at day 7 and day 14. Additionally, significantly higher gene expressions of Col-2, Acan, and Sox-9 (p < 0.01) were found in IPN hydrogel groups when compared with the GelMA group. An in vivo study was performed to confirm that the GelMA-SF IPN hydrogel could promote cartilage regeneration. The results showed partial regeneration of cartilage in groups treated with hydrogels only and satisfactory cartilage repair in groups of cell-seeded hydrogels, indicating the necessity of additional seeding cells in hydro-gel-based cartilage treatment. Therefore, our results suggest that the GelMA/SF IPN hydrogels may be a potential functional material in cartilage repair and regeneration.

The effect of chondroitin sulfate concentration and matrix stiffness on chondrogenic differentiation of mesenchymal stem cells.

Chondroitin sulfate (CS), a glycosaminoglycan of native cartilage, has shown its potential in promoting chondrogenesis of mesenchymal stem cells (MSCs), whereas the effect of matrix stiffness in a CS-containing 3D environment on chondrogenesis is still poorly understood. Herein, this study aimed at assessing the effect of CS concentration and stiffness of CS-containing hydrogels on the chondrogenesis of MSCs. Hydrogels composed of 6% (w/v) gelatin methacryloyl (GelMA) and three concentrations, i.e., 4%, 6%, or 10% (w/v), of methacrylated chondroitin sulfate (CSMA) were prepared. The hydrogels of each composition were prepared with two stiffness values (33.36 ± 8.25 kPa vs. 8.42 ± 2.83 kPa). Physical characterization showed similar microporous structures among the six groups, higher swelling ratios and faster degradation in the soft hydrogel groups. MSCs were encapsulated in the six groups of hydrogels and they underwent 28-day chondrogenic differentiation. The cell viability in each group on day 1 was similar and most cells exhibited a round shape without spreading. Afterwards, cellular protrusions in soft hydrogels remained filopodium-like from day 14 to day 28, while most protrusions were lamellipodium-like in stiff hydrogels on day 14 and then transformed into a spherical shape on day 28. The expression of chondrogenic markers analysed by real-time qPCR and immunohistochemical staining demonstrated that the optimal CS concentration for chondrogenesis was 6% (w/v) regardless of the stiffness of hydrogels. In addition, with the same CSMA concentration, the trend was observed that the stiff hydrogels supported superior chondrogenesis of MSCs compared to the soft hydrogel. To summarize, this study presents an advancement in the optimization of CSMA concentration and stiffness of hydrogels for chondrogenesis. In the CSMA/GelMA hydrogel, 6% (w/v) CSMA with an initial Young's modulus around 33 kPa was recommended for cartilage tissue engineering.

Crack propagation and arrests in gelatin hydrogels are linked to tip curvatures.

Gelatin hydrogels are attractive scaffold materials for tissue engineering applications as they provide motifs for cell attachment, undergo large deformations, and are tunable. Low toughness and brittle fractures however limit their use in load bearing applications. An investigation of crack tip processes and mechanisms of crack propagation is warranted to link fracture properties with material microstructure. We cross-linked gelatin using glutaraldehyde to obtain low cross-linked control hydrogels and used an additional cross-linker, methylglyoxal, to fabricate MGO hydrogels with higher cross-links. We quantified fractures in the gelatin hydrogels from both groups using pure shear notch tests and characterized strain fields near the crack tip using 2-D digital image correlation. We used a numerical method based on Taylor's series expansion to measure the crack tip curvatures in the hydrogels. This method captures tip curvatures better than the parabolic method routinely used in studies. Results from our study show that cracks in gelatin hydrogels underwent frequent arrests during propagation through the specimen width in both groups. MGO hydrogels had 85% enhanced fracture toughness and a significantly higher number of stalls compared to the control group. Crack initiations following stalls in the sample correlated with low tip curvatures in both hydrogel groups. We also show that mechanical stretching blunts the crack tip before crack propagation; the degree of blunting was independent of the cross-link density and elastic modulus of the gelatin hydrogels. These results show a link between crack growth and the tip curvature in cross-linked gelatin hydrogels, and offer potential insights for the development of tougher hydrogels.

The Effect of The Topical Application of Eurycoma Longifolia Jack (TA) Root Extract Hydrogel on Vascular Endothelial Growth Factor (VEGF) Expression During Wound Healing in vivo Excisional Wound Model

INTRODUCTION: Medicinal plants are known for their positive impacts on wound healing by stimulating angiogenesis in the skin. Eurycoma longifolia Jack locally known as Tongkat Ali (TA), is a medicinal plant characterised by anti-inflammatory and antioxidant effects. MATERIALS AND METHODS: Excisional wound (15mm × 15mm) in diameter and (2mm) depth was created at the back of 20 male Sprague Dawley rats by incising the marked skin with sterilized surgical scalpel blade then excised the skin by surgical scissors and toothed forceps. The wounded rats were divided into 4 groups, each group contained 5 rats (n=5). Experimental groups were formed as follows: untreated (-ve) control, Hydrocyn® aqua gel (+ve) control, vehicle hydrogel, and TA hydrogel. All the treatments were applied twice daily for 5 days starting on the first day (wounding day). On Day 5 post-wounding, the granulation tissue was harvested from all groups and evaluated by immunohistochemistry assay for Vascular endothelial growth factor (VEGF) expression. RESULTS: VEGF expression in granulation tissue of rat’s skin treated with TA hydrogel and vehicle hydrogel increased significantly compared to that in the untreated (-ve) control group with p-values of 0.040 and 0.029, respectively. Although there was no significant difference in VEGF expression in granulation tissue of rat’s skin treated with the TA group, Hydrocyn® aqua gel (+ve) control, and vehicle hydrogel groups, our study group showed higher expression of VEGF. CONCLUSION: Our study showed that the topical application of TA hydrogel increased the VEGF expression in granulation tissue of rat’s skin, which is an essential growth factor for wound healing. Thus, there is great potential for TA hydrogel to be an effective wound-healing agent for managing cutaneous wounds.

Design of Adhesive Hemostatic Hydrogels Guided by the Interfacial Interactions with Tissue Surface

Adhesive hemostatic hydrogels, as one of the most important wound dressings, have attracted tremendous attention because of their unique advantages in injured tissue. Many intensive efforts are devoted to designing ingenious adhesive hemostatic hydrogels based on interfacial interactions with tissue surfaces, such as covalent bonds, hydrogen bonds, electrostatic interactions, cation–π interactions, and π–π stacking interactions. Herein, an overview of the recent progress in adhesive hemostatic hydrogels is provided, especially focusing on diverse covalent/noncovalent interfacial interactions between the active groups of adhesive hydrogels and tissue surface. The commonly used forms and the hemostatic evaluation models of the adhesive hydrogels are also summarized. Finally, the critical issues that should be concerned for current adhesive hemostatic hydrogels and the developing directions toward practical applications are discussed.