Reducing posttreatment relapse in cleft lip palatal expansion using an injectable estrogen-nanodiamond hydrogel.

Patients with cleft lip and/or palate (CLP), who undergo numerous medical interventions from infancy, can suffer from lifelong debilitation caused by underdeveloped maxillae. Conventional treatment approaches use maxillary expansion techniques to develop normal speech, achieve functional occlusion for nutrition intake, and improve esthetics. However, as patients with CLP congenitally lack bone in the cleft site with diminished capacity for bone formation in the expanded palate, more than 80% of the patient population experiences significant postexpansion relapse. While such relapse has been a long-standing battle in craniofacial care of patients, currently there are no available strategies to address this pervasive problem. Estrogen, 17ß-estradiol (E2), is a powerful therapeutic agent that plays a critical role in bone homeostasis. However, E2's clinical application is less appreciated due to several limitations, including its pleiotropic effects and short half-life. Here, we developed a treatment strategy using an injectable system with photo-cross-linkable hydrogel (G) and nanodiamond (ND) technology to facilitate the targeted and sustained delivery of E2 to promote bone formation. In a preclinical expansion/relapse model, this functionalized E2/ND/G complex substantially reduced postexpansion relapse by nearly threefold through enhancements in sutural remodeling compared with unmodified E2 administration. The E2/ND/G group demonstrated greater bone volume by twofold and higher osteoblast number by threefold, compared with the control group. The E2/ND/G platform maximized the beneficial effects of E2 through its extended release with superior efficacy and safety at the local level. This broadly applicable E2 delivery platform shows promise as an adjuvant therapy in craniofacial care of patients.

Shear-wave elasticity measurements of three-dimensional cell cultures for mechanobiology.

Studying mechanobiology in three-dimensional (3D) cell cultures better recapitulates cell behaviors in response to various types of mechanical stimuli in vivo Stiffening of the extracellular matrix resulting from cell remodeling potentiates many pathological conditions, including advanced cancers. However, an effective tool for measuring the spatiotemporal changes in elastic properties of such 3D cell cultures without directly contacting the samples has not been reported previously. We describe an ultrasonic shear-wave-based platform for quantitatively evaluating the spatiotemporal dynamics of the elasticity of a matrix remodeled by cells cultured in 3D environments. We used this approach to measure the elasticity changes of 3D matrices grown with highly invasive lung cancer cells and cardiac myoblasts, and to delineate the principal mechanism underlying the stiffening of matrices remodeled by these cells. The described approach can be a useful tool in fields investigating and manipulating the mechanotransduction of cells in 3D contexts, and also has potential as a drug-screening platform.

Encapsulated explant in novel low shear perfusion bioreactor improve cell isolation, expansion and colony forming unit.

One of most important issue in the field of regenerative medicine is selection of appropriate cells, scaffolds and bioreactors. The present study aimed to investigate the appropriate method for the isolation of human UC-MSCs cells from explant cultured in alginate scaffold within novel perfusion bioreactor. MSCs were isolated with explant method and CD markers such CD73, CD31, CD90 and CD105 as were analyzed by flow cytometry. The culture chamber of the novel perfusion bioreactor was made from Plexiglas and housed the cell/scaffold constructs in the central part and the medium for the whole culture period. The flow behavior within the bioreactor chamber were performed for closed and open bypass systems. The shear stress profiles simulated using CFD modeling. The fluid flow distribution within the bioreactor chamber was performed in PBS solution containing a blue colorant. UC explants were resuspended in sodium alginate and were allowed to polymerize and placed in the perfusion bioreactor and cultured. MSCs were positive for mesenchymal markers such as CD73 and CD31. All 3D Perfusion bioreactor parts, except peristaltic pump was sterilizable by autoclaving. Results of CFD indicated very low wall shear stress on surface of culture chamber at flow rate 2 ml/min. The maximum wall shear stress was 1.10 × 10-3 m/s = 0.0110 dyne/cm2 (1 Pa = 10 dyne/cm2). The fluid flow distribution within the alginate gel initially exhibited oscillation. In comparison, when encapsulated explants were placed in the perfusion bioreactor, cell proliferation appeared faster (4.6 × 1011 ± 9.2 × 1011) than explants cultures in 2D conventional culture method (3.2 × 1011 ± 1 × 1011). Proliferated cell formed several colonies. Migration of chondrocytes to the periphery of the alginate bead was visible after 1 week of culture. Perfusion bioreactor with low shear stress and alginate hydrogel improve cell isolation and expansion and eliminate cell passaging and enhance colony forming unit of UC-MSCs.

Multicellular Co-Culture in Three-Dimensional Gelatin Methacryloyl Hydrogels for Liver Tissue Engineering.

Three-dimensional (3D) tissue models replicating liver architectures and functions are increasingly being needed for regenerative medicine. However, traditional studies are focused on establishing 2D environments for hepatocytes culture since it is challenging to recreate biodegradable 3D tissue-like architecture at a micro scale by using hydrogels. In this paper, we utilized a gelatin methacryloyl (GelMA) hydrogel as a matrix to construct 3D lobule-like microtissues for co-culture of hepatocytes and fibroblasts. GelMA hydrogel with high cytocompatibility and high structural fidelity was determined to fabricate hepatocytes encapsulated micromodules with central radial-type hole by photo-crosslinking through a digital micromirror device (DMD)-based microfluidic channel. The cellular micromodules were assembled through non-contact pick-up strategy relying on local fluid-based micromanipulation. Then the assembled micromodules were coated with fibroblast-laden GelMA, subsequently irradiated by ultraviolet for integration of the 3D lobule-like microtissues encapsulating multiple cell types. With long-term co-culture, the 3D lobule-like microtissues encapsulating hepatocytes and fibroblasts maintained over 90% cell viability. The liver function of albumin secretion was enhanced for the co-cultured 3D microtissues compared to the 3D microtissues encapsulating only hepatocytes. Experimental results demonstrated that 3D lobule-like microtissues fabricated by GelMA hydrogels capable of multicellular co-culture with high cell viability and liver function, which have huge potential for liver tissue engineering and regenerative medicine applications.

Novel nanohydrogel of hyaluronic acid loaded with quercetin alone and in combination with temozolomide as new therapeutic tool, CD44 targeted based, of glioblastoma multiforme.

Glioblastoma multiforme is the most common and aggressive primary brain cancer with only ∼3% of patients surviving more than 3 years from diagnosis. Several mechanisms are involved in drug and radiation resistance to anticancer treatments and among them one of the most important factors is the tumor microenvironment status, characterized by cancer cell hypersecretion of interleukins and cytokines. The aim of our research was the synthesis of a nanocarrier of quercetin combined with temozolomide, to enhance the specificity and efficacy of this anticancer drug commonly used in glioblastoma treatment. The nanohydrogel increased the internalization and cytotoxicity of quercetin in human glioblastoma cells and, when co-delivered with temozolomide, contribute to an improved anticancer effect. The nanohydrogel loaded with quercetin had the ability to recognize CD44 receptor, a brain cancer cell marker, through an energy and caveolae dependent mechanism of internalization. Moreover, nanohydrogel of quercetin was able to reduce significantly IL-8, IL-6, and VEGF production in pro-inflammatory conditions with interesting implications on the mechanism of glioblastoma cells drug resistance. In summary, novel CD44 targeted polymeric based nanocarriers appear to be proficient in mediating site-specific delivery of quercetin via CD44 receptor in glioblastoma cells. This targeted therapy lead to an improved therapeutic efficacy of temozolomide by modulating the brain tumor microenvironment.

Enzymatic degradation of hyaluronan hydrogels with different capacity for in situ bio-mineralization.

In situ cross-linked hyaluronan (HA) hydrogels with different capacities for biomineralization were prepared and their enzymatic degradation was monitored. Covalent incorporation of bisphosphonates (BPs) into HA hydrogel results in the increased stiffness of the hydrogel in comparison with the unmodified HA hydrogel of the same cross-linking density. The rate of enzymatic degradation of HABP hydrogel was significantly lower than the rate of degradation of control HA hydrogel in vitro. This effect is observed only in the presence of calcium ions that strongly bind to the matrix-anchored BP groups and promote further mineralization of the matrix. The degradation of the hydrogels was followed by noninvasive fluorescence measurements enabled after mild and chemoselective labeling of cross-linkable HA derivatives with a fluorescent tag.

Injectable Self-Healing Zwitterionic Hydrogels Based on Dynamic Benzoxaborole-Sugar Interactions with Tunable Mechanical Properties.

Dynamic hydrogels based on arylboronic esters have been considered as ideal platforms for biomedical applications given their self-healing and injectable characteristics. However, there still exist some critical issues that need to be addressed or improved, including hydrogel biocompatibility, physiological usability, and tunability of mechanical properties. Here, two kinds of phospholipid bioinspired MPC copolymers, one is zwitterionic copolymer (PMB) containing a fixed 15 mol % of benzoxaborole (pKa ≈ 7.2) groups and the other is zwitterionic glycopolymers (PMG) with varied ratios of sugar groups (20%, 50%, 80%), were synthesized respectively via one-pot facile reversible addition-fragmentation chain transfer (RAFT) polymerization. PMBG hydrogels were formed spontaneously after mixing 10 wt % of PMB and PMG copolymer solutions because of dynamic benzoxaborole-sugar interactions. The mechanical properties of nine hydrogels (3 × 3) with different sugar contents and pHs (7.4, 8.4, 9.4) were carefully studied by rheological measurements, and hydrogels with higher sugar content and higher pH were found to have higher strength. Moreover, similar to other arylboronic ester-based hydrogels, PMBG hydrogels possessed not only self-healing and injectable properties but also pH/sugar responsiveness. Additionally, in vitro cytotoxicity tests of gel extracts on both normal and cancer cells further confirmed the excellent biocompatibility of the hydrogels, which should be ascribed to the biomimetic nature of phosphorylcholine (PC) and sugar residues of the copolymers. Consequently, the zwitterionic dynamic hydrogels provide promising future for diverse biomedical applications.

Self-Healing Hydrogels of Low Molecular Weight Poly(vinyl alcohol) Assembled by Host-Guest Recognition.

Poly(vinyl alcohol) (PVA) is a cytocompatible synthetic polymer and has been commonly used to prepare hydrogels. Bile acids and ß-cyclodextrin are both natural compounds and they form stable host-guest inclusion complexes. They are attached covalently onto a low molecular weight PVA separately. Self-healing hydrogels can be easily formed by mixing the aqueous solutions of these PVA based polymers. The mechanical properties of the hydrogels can be tuned by varying the molar fractions of bile acid units on PVA. The dynamic inclusion complexation of the host-guest pair of the hydrogel allows the self-healing rapidly under ambient atmosphere and their mechanical properties could recover their original values in 1 min after incision. These PVA based polymers exhibited the good cytocompatibility and high hemocompatibility as shown by their biological evaluations. The use of natural compounds for host-guest interaction make such gels especially convenient to use as biomaterials, an advantage over conventional hydrogels prepared through freeze-thaw method.

Squaramide-Based Supramolecular Materials for Three-Dimensional Cell Culture of Human Induced Pluripotent Stem Cells and Their Derivatives.

Synthetic hydrogel materials can recapitulate the natural cell microenvironment; however, it is equally necessary that the gels maintain cell viability and phenotype while permitting reisolation without stress, especially for use in the stem cell field. Here, we describe a family of synthetically accessible, squaramide-based tripodal supramolecular monomers consisting of a flexible tris(2-aminoethyl)amine (TREN) core that self-assemble into supramolecular polymers and eventually into self-recovering hydrogels. Spectroscopic measurements revealed that monomer aggregation is mainly driven by a combination of hydrogen bonding and hydrophobicity. The self-recovering hydrogels were used to encapsulate NIH 3T3 fibroblasts as well as human-induced pluripotent stem cells (hiPSCs) and their derivatives in 3D. The materials reported here proved cytocompatible for these cell types with maintenance of hiPSCs in their undifferentiated state essential for their subsequent expansion or differentiation into a given cell type and potential for facile release by dilution due to their supramolecular nature.

Visible Light-Induced Hydrogelation of an Alginate Derivative and Application to Stereolithographic Bioprinting Using a Visible Light Projector and Acid Red.

Visible light-induced hydrogelation is attractive for various biomedical applications. In this study, hydrogels of alginate with phenolic hydroxyl groups (Alg-Ph) were obtained by irradiating a solution containing the polymer, ruthenium II trisbipyridyl chloride ([Ru(bpy)3]2+) and sodium persulfate (SPS), with visible light. The hydrogelation kinetics and the mechanical properties of the resultant hydrogels were tunable by controlling the intensity of the light and the concentrations of [Ru(bpy)3]2+ and SPS. With appropriate concentrations of [Ru(bpy)3]2+ and SPS, the hydrogel could be obtained following approximately 10 s of irradiation using a normal desktop lamp. The hydrogelation process and the resultant hydrogel were cytocompatible; mouse fibroblast cells enclosed in the Alg-Ph hydrogel maintained more than 90% viability for 1 week. The solution containing Alg-Ph, [Ru(bpy)3]2+ and SPS was useful as a bioink for stereolithographic bioprinting. Cell-laden hydrogel constructs could be printed using the bioprinting system equipped with a visible light projector without a significant decrease in cell viability in the presence of photoabsorbent Acid Red 18. The hydrogel construct including a perfusable helical lumen of 1 mm in diameter could be fabricated using the printing system. These results demonstrate the significant potential of this visible light-induced hydrogelation system and the stereolithographic bioprinting using the hydrogelation system for tissue engineering and regenerative medicine.

3D bioprinting mesenchymal stem cell-laden construct with core-shell nanospheres for cartilage tissue engineering.

Cartilage tissue is prone to degradation and has little capacity for self-healing due to its avascularity. Tissue engineering, which provides artificial scaffolds to repair injured tissues, is a novel and promising strategy for cartilage repair. 3D bioprinting offers even greater potential for repairing degenerative tissue by simultaneously integrating living cells, biomaterials, and biological cues to provide a customized scaffold. With regard to cell selection, mesenchymal stem cells (MSCs) hold great capacity for differentiating into a variety of cell types, including chondrocytes, and could therefore be utilized as a cartilage cell source in 3D bioprinting. In the present study, we utilize a tabletop stereolithography-based 3D bioprinter for a novel cell-laden cartilage tissue construct fabrication. Printable resin is composed of 10% gelatin methacrylate (GelMA) base, various concentrations of polyethylene glycol diacrylate (PEGDA), biocompatible photoinitiator, and transforming growth factor beta 1 (TGF-ß1) embedded nanospheres fabricated via a core-shell electrospraying technique. We find that the addition of PEGDA into GelMA hydrogel greatly improves the printing resolution. Compressive testing shows that modulus of the bioprinted scaffolds proportionally increases with the concentrations of PEGDA, while swelling ratio decreases with the increase of PEGDA concentration. Confocal microscopy images illustrate that the cells and nanospheres are evenly distributed throughout the entire bioprinted construct. Cells grown on 5%/10% (PEGDA/GelMA) hydrogel present the highest cell viability and proliferation rate. The TGF-ß1 embedded in nanospheres can keep a sustained release up to 21 d and improve chondrogenic differentiation of encapsulated MSCs. The cell-laden bioprinted cartilage constructs with TGF-ß1-containing nanospheres is a promising strategy for cartilage regeneration.

Osteogenic efficacy of BMP-2 mixed with hydrogel and bone substitute in peri-implant dehiscence defects in dogs: 16 weeks of healing.

OBJECTIVES: The objective of this study was to determine the effect of bone morphogenetic protein-2 (BMP-2) mixed with either polyethylene glycol hydrogel or synthetic bone substitute (SBS) on new bone formation in peri-implant dehiscence defects after 16 weeks of healing. MATERIALS AND METHODS: A guided bone regeneration procedure was performed in box-type peri-implant defects that were surgically prepared in six beagle dogs. The following four experimental groups were used (i) control (no graft), (ii) SBS+hydrogel, (iii) SBS+BMP-2/hydrogel and (iv) BMP-2/SBS+hydrogel. Volumetric analysis using micro-computed tomography and histomorphometric analysis was performed at 16 weeks post-operatively. RESULTS: The amount of new bone and the total augmented volume did not differ significantly between both BMP-treated groups and the SBS+hydrogel group (p > .05). Likewise, no histometric differences were observed in the values of new bone area and bone-to-implant contact ratio among the three augmentation groups (new bone area: 0.06 ± 0.08, 0.19 ± 0.20, 0.48 ± 0.37 and 0.56 ± 0.60 mm2 [mean ± standard deviation] in groups 1-4, respectively; bone-to-implant contact: 9.44 ± 11.51%, 19.91 ± 15.19%, 46.31 ± 29.82% and 42.58 ± 26.27% in groups 1-4, respectively). CONCLUSION: The osteogenic efficacy of BMP-2 on the regeneration of peri-implant bone defects was not detectable after 16 weeks regardless of the carrier materials.

Hydrogel-laden paper scaffold system for origami-based tissue engineering.

In this study, we present a method for assembling biofunctionalized paper into a multiform structured scaffold system for reliable tissue regeneration using an origami-based approach. The surface of a paper was conformally modified with a poly(styrene-co-maleic anhydride) layer via initiated chemical vapor deposition followed by the immobilization of poly-l-lysine (PLL) and deposition of Ca(2+). This procedure ensures the formation of alginate hydrogel on the paper due to Ca(2+) diffusion. Furthermore, strong adhesion of the alginate hydrogel on the paper onto the paper substrate was achieved due to an electrostatic interaction between the alginate and PLL. The developed scaffold system was versatile and allowed area-selective cell seeding. Also, the hydrogel-laden paper could be folded freely into 3D tissue-like structures using a simple origami-based method. The cylindrically constructed paper scaffold system with chondrocytes was applied into a three-ring defect trachea in rabbits. The transplanted engineered tissues replaced the native trachea without stenosis after 4 wks. As for the custom-built scaffold system, the hydrogel-laden paper system will provide a robust and facile method for the formation of tissues mimicking native tissue constructs.

Alginate Encapsulation to Enhance Biopreservation Scope and Success: A Multidisciplinary Review of Current Ideas and Applications in Cryopreservation and Non-Freezing Storage.

BACKGROUND: The development of encapsulation technologies has played an important role in improving cryopreservation outcomes for many cell and tissue types over the past 20 years. Alginate encapsulation cryopreservation (AECryo) has been incorporated into a range of applications in biotechnology, species conservation and clinical therapies, using cells from many different phyla, including higher plants, animal and human cells. This review describes the background to the origins of AECryo, the development of AECryo in higher plant tissues, broadening to current applications in algal conservation, the roles for AECryo in preserving phytodiversity, fungal species and in animal and human cells. OBJECTIVE: The main aims are to provide information resources on AECryo in different areas of biology and to stimulate new ideas for wider applications and future improvement. The translation of this useful biopreservation strategy into new opportunities for cell cryopreservation and storage at non-freezing temperatures are also discussed.

Assessment of Chitosan-Based Hydrogel and Photodynamic Inactivation against Propionibacterium acnes.

Chitosan (CH) is a biopolymer that exhibits a number of interesting properties such as anti-inflammatory and antibacterial activity and is also a promising platform for the incorporation of photosensitizing agents. This study aimed to evaluate the efficacy of antimicrobial activity of chitosan hydrogel formulation alone and in combination with the methylene blue (MB) associated with antimicrobial photodynamic therapy (aPDT) against planktonic and biofilm phase of Propionibacterium acnes. Suspensions were sensitized with 12.5, 25.0, 37.5, 50.0 µg/mL of MB for 10 min and biofilms to 75, 100 and 150 µg/mL for 30 min then exposed to red light (660 nm) at 90 J/cm² and 150 J/cm² respectively. After treatments, survival fractions were calculated by counting the number of colony-forming units. The lethal effect of aPDT associated with CH hydrogel in planktonic phase was achieved with 12.5 µg/mL MB and 1.9 log10 biofilm reduction using 75 µg/mL MB. Rheological studies showed that formulations exhibited pseudoplastic non-Newtonian behavior without thixotropy. Bioadhesion test evidenced that the formulations are highly adhesive to skin and the incorporation of MB did not influence the bioadhesive force of the formulations.

Effects of Hydrogel With Enriched Sodium Alginate in Wounds of Diabetic Patients.

Objective of this study was to evaluate the efficacy of the autolytic debridement promoted by hydrogel with sodium alginate enriched with fatty acids and vitamins A and E in the healing of foot wounds in diabetic patients. A clinical study was conducted at an outpatient clinic of medical specialties. The sample comprised 8 patients supervised for a 3-month period, from April to July 2017, by means of a clinical history, photographic record, planimetry, and classification of the wound severity by the Pressure Ulcer Scale for Healing (PUSH) system. Of the 8 patients supervised, 1 dropped out and 7 were followed up for 12 weeks. Only 2 had complete wound healing, but all presented a reduction of the lesion area of approximately 22.2% and PUSH score of 9.8 to 6.6. This study found that hydrogel showed good results for the treatment of diabetic feet, reducing the area and overall PUSH score of the wounds.

Mechanically tuned 3 dimensional hydrogels support human mammary fibroblast growth and viability.

BACKGROUND: Carcinoma associated fibroblasts (CAFs or myofibroblasts) are activated fibroblasts which participate in breast tumor growth, angiogenesis, invasion, metastasis and therapy resistance. As such, recent efforts have been directed toward understanding the factors responsible for activation of the phenotype. In this study, we have investigated how changes in the mechanical stiffness of a 3D hydrogel alter the behavior and myofibroblast-like properties of human mammary fibroblasts (HMFs). RESULTS: Here, we utilized microbial transglutaminase (mTG) to mechanically tune the stiffness of gelatin hydrogels and used rheology to show that increasing concentrations mTG resulted in hydrogels with greater elastic moduli (G'). Upon encapsulation of HMFs in 200 (compliant), 300 (moderate) and 1100 Pa (stiff) mTG hydrogels, it was found that the HMFs remained viable and proliferated over the 7 day culture period. Specifically, rates of proliferation were greatest for HMFs in moderate hydrogels. Regarding morphology, HMFs in compliant and moderate hydrogels exhibited a spindle-like morphology while HMFs in stiff hydrogels exhibited a rounded morphology with several large cellular protrusions. Quantification of cell morphology revealed that HMFs cultured in all mTG hydrogels overall assumed a more elongated phenotype over time in culture; however, few significant differences in morphology were observed between HMFs in each of the hydrogel conditions. To determine whether matrix stiffness upregulated expression of ECM and myofibroblast markers, western blot was performed on HMFs in compliant, moderate and stiff hydrogels. It was found that ECM and myofibroblast proteins varied in expression during both the culture period and according to matrix stiffness with no clear correlation between matrix stiffness and a myofibroblast phenotype. Finally, TGF-ß levels were quantified in the conditioned media from HMFs in compliant, moderate and stiff hydrogels. TGF-ß was significantly greater for HMFs encapsulated in stiff hydrogels. CONCLUSIONS: Overall, these results show that while HMFs are viable and proliferate in mTG hydrogels, increasing matrix stiffness of mTG gelatin hydrogels doesn't support a robust myofibroblast phenotype from HMFs. These results have important implications for further understanding how modulating 3D matrix stiffness affects fibroblast morphology and activation into a myofibroblast phenotype.

A Topical Hydrogel with Deferiprone and Gallium-Protoporphyrin Targets Bacterial Iron Metabolism and Has Antibiofilm Activity.

Many infectious diseases are associated with multidrug-resistant (MDR) bacteria residing in biofilms that require high antibiotic concentrations. While oral drug delivery is frequently ineffective, topical treatments have the potential to deliver higher drug concentrations to the infection site while reducing systemic side effects. This study determined the antibiofilm activity of a surgical wound gel loaded with the iron chelator deferiprone (Def) and the heme analogue gallium-protoporphyrin (GaPP), alone and in combination with ciprofloxacin. Activity against MDR Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Acinetobacter johnsonii biofilms was assessed in the colony biofilm and artificial wound model by enumeration of CFU and correlative light/electron microscopy. While Staphylococcus biofilms were equally susceptible to GaPP and Def-GaPP gels (log10 reduction of 3.8 and 3.7, respectively), the Def-GaPP combination was crucial for significant activity against P. aeruginosa biofilms (log10 reduction of 1.3 for GaPP and 3.3 for Def-GaPP). When Def-GaPP gel was combined with ciprofloxacin, the efficacy exceeded the activity of the individual compounds. Def-GaPP delivered in a surgical wound gel showed significant antibiofilm activity against different MDR strains and could enhance the gel's wound-healing properties. Moreover, Def-GaPP indicated a potentiation of ciprofloxacin. This antibiofilm strategy has potential for clinical utilization as a therapy for topical biofilm-related infections.

Human umbilical cord blood-derived mesenchymal stromal cells and small intestinal submucosa hydrogel composite promotes combined radiation-wound healing of mice.

BACKGROUND AIMS: Mesenchymal stromal cells (MSCs) are a promising agent for treating impaired wound healing, and their therapeutic potential may be enhanced by employing extracellular matrix scaffolds as cell culture scaffolds or transplant cell carriers. Here, we evaluated the effect of human umbilical cord blood-derived (hUCB)-MSCs and a porcine small intestinal submucosa (SIS)-derived extracellular matrix scaffold in a combined radiation-wound mouse model of impaired wound healing. METHODS: hUCB-MSCs and SIS hydrogel composite was applied to the excisional wound of whole-body irradiated mice. Assessment of wound closing and histological evaluation were performed in vivo. We also cultured hUCB-MSCs on SIS gel and examined the angiogenic effect of conditioned medium on irradiated human umbilical vein endothelial cells (HUVECs) in vitro. RESULTS: hUCB-MSCs and SIS hydrogel composite treatment enhanced wound healing and angiogenesis in the wound site of mice. Conditioned medium from hUCB-MSCs cultured on SIS hydrogel promoted the chemotaxis of irradiated HUVECs more than their proliferation. The secretion of angiogenic growth factors hepatocyte growth factor, vascular endothelial growth factor-A and angiopoietin-1 from hUCB-MSCs was significantly increased by SIS hydrogel, with HGF being the predominant angiogenic factor of irradiated HUVECs. CONCLUSIONS: Our results suggest that the wound healing effect of hUCB-MSCs is enhanced by SIS hydrogel via a paracrine factor-mediated recruitment of vascular endothelial cells in a combined radiation-wound mouse model.

In situ forming oxidised hyaluronic acid/adipic acid dihydrazide hydrogel for prevention of epidural fibrosis after laminectomy.

Post-operative epidural fibrosis is a biological response after laminectomy that may lead to clinical symptoms, such as radicular pain. An ideal material for prevention of epidural fibrosis should be able to inhibit fibroblast adhesions and reduce formation of scar tissue. An injectable hydrogel would be the material of choice for this purpose, since it could fill an irregular surgical defect completely, gelate in situ and be delivered in a minimally-invasive manner. The objective of this study was to evaluate, in vitro and in vivo, the cytocompatibility and anti-adhesive effect of an oxidised hyaluronic acid/adipic acid dihydrazide (oxi-HA/ADH) hydrogel. Different cell types present in the spine were used to test the cytocompatibility of the hydrogel. The hydrogel extraction medium had no deleterious effects on neural cells (PC-12), but reduced fibroblasts viability (NIH/3T3). Although the hydrogel did not change the release of lactate dehydrogenase from myoblasts (C2C12) and Schwann cells (RSC96), the extraction medium concentration slightly affected the mitochondrial activity of these two cell types. qPCR showed that the hydrogel down-regulated S100a and P4hb expression in NIH/3T3 cells, supporting the hypothesis that the hydrogel might inhibit fibroblast activity. The animal study showed a reduction of scar tissue formation as well as severity of adhesion between scar tissue and the dura mater in a rat laminectomy model. Superficially, the peel-off test showed significantly decreased tenacity. In conclusion, the oxi-HA/ADH hydrogel is a promising injectable and thermosensitive material for prevention of post-operative epidural fibrosis.