Sponge Scaffold Research Articles

Repairing Cartilage with Processed Chondrocyte Constructs: A 6-Month Study Using a Porcine Model.

Autologous chondrocyte implantation was the first cell-based therapy that used a tissue engineering process to repair cartilage defects. Recently improved approaches and tissue-engineered cell constructs have been developed for growing patient populations. We developed a chondrocyte construct using a collagen gel and sponge scaffold and physicochemical stimuli, implanted with a surgical adhesive. We conducted a proof-of-concept study of these improvements using a cartilage defect model in miniature swine. We implanted the autologous chondrocyte constructs into full-thickness chondral defects in the femoral condyle, compared those results with empty and acellular scaffold controls, and compared implantation techniques with adhesive alone and with partial adhesive with suture. Two weeks after the creation of the defects and implantation of the cellular or acellular constructs, we arthroscopically confirmed that the implanted constructs remained at the chondral defects. We evaluated the regenerated tissue macro- and microscopically 6 months after the cell constructs were implanted. The tissues were stained with Safranin-O and evaluated using Sellers' histology grading system. The defects implanted with processed cell constructs and acellular scaffolds were filled with chondrocyte-like round cells and with nearly normal tissue architecture that were significantly greater degree compared to empty defect control. Even with the adhesive alone and with suture alone, the cell construct was composed of the dense cartilaginous matrix that was found in the implantation using both the sutures and the adhesive. Implantation of cell constructs promoted regeneration and integration of articular cartilage at chondral defects in swine by 6 months.

Comparison of three different skin substitutes in promoting wound healing in an ovine model

Skin substitutes are designed dressings intended to promote wound closure. In previous in vitro and in vivo studies on small animal, an acellular skin patch made of collagen hydrogel with dermal fibroblast conditioned medium (Col-DFCM), a collagen sponge scaffold with freshly harvested skin cells (OTC), and a platelet-rich-plasma gel with freshly harvested skin cells (PRP) have been developed and tested for immediate treatment of full-thickness wound. However, to determine the safety and efficacy of these skin patches for clinical applications, further study in a large animal model is needed. The aim of this study is to evaluate the potential of Col-DFCM, OTC and PRP in treating full-thickness wound in an ovine model via histological analysis and immunohistochemistry staining were performed, with the untreated (NT) group serving as the control. Gross examination was conducted on day 7, 14 and 21 to determine the wound closure rate. The findings of percentage of wound size reduction showed that the wound healed fastest in the presence of Col-DFCM (91.34 ± 23.35%) followed by OTC (84.49 ± 23.13%), PRP (77.73 ± 20.9%) and NT group (73.94 ± 23.71%). Histological evaluation with Hematoxylin & Eosin (H & E) and Masson’s trichrome staining was used to study the structure of the wound area. The results showed that OTC treated wound was more mature as indicated by the presence of a thinner epidermis followed by the Col-DFCM, PRP and NT group. Immunohistochemistry analysis also confirmed the integrity and maturity of the regenerated skin, with positive expression of cytokeratin 10 (CK10) and involucrin in the epidermal layer. In conclusion, Col-DFCM, OTC and PRP treatments promote healing of full-thickness wound and have the potential to be used clinically for rapid treatment of full-thickness wound.

An NT-3-releasing bioscaffold supports the formation of TrkC-modified neural stem cell-derived neural network tissue with efficacy in repairing spinal cord injury

The mechanism underlying neurogenesis during embryonic spinal cord development involves a specific ligand/receptor interaction, which may be help guide neuroengineering to boost stem cell-based neural regeneration for the structural and functional repair of spinal cord injury. Herein, we hypothesized that supplying spinal cord defects with an exogenous neural network in the NT-3/fibroin-coated gelatin sponge (NF-GS) scaffold might improve tissue repair efficacy. To test this, we engineered tropomyosin receptor kinase C (TrkC)-modified neural stem cell (NSC)-derived neural network tissue with robust viability within an NF-GS scaffold. When NSCs were genetically modified to overexpress TrkC, the NT-3 receptor, a functional neuronal population dominated the neural network tissue. The pro-regenerative niche allowed the long-term survival and phenotypic maintenance of the donor neural network tissue for up to 8 weeks in the injured spinal cord. Additionally, host nerve fibers regenerated into the graft, making synaptic connections with the donor neurons. Accordingly, motor function recovery was significantly improved in rats with spinal cord injury (SCI) that received TrkC-modified NSC-derived neural network tissue transplantation. Together, the results suggested that transplantation of the neural network tissue formed in the 3D bioactive scaffold may represent a valuable approach to study and develop therapies for SCI.

Three-Dimensional Macroporous Sponge for the Culture of Hepatocellular Carcinoma Patient-Derived Xenograft Organoids.

This protocol focuses on the culture of cells harvested from hepatocellular carcinoma (HCC) patient-derived xenografts (PDXs) as organoids using a cellulosic macroporous sponge scaffold. Compared with many other epithelial cancer types, the viability of HCC cells directly derived from patients or PDX models is notoriously challenging to maintain in vitro. We previously developed a macroporous sponge scaffold uniquely designed to provide biochemical and mechanical cues that support the culture of normal hepatocytes as spheroids with maintained functionality. Leveraging our success using this sponge scaffold to maintain normal hepatocytes in vitro, we recently demonstrated that a similar sponge scaffold enables the maintenance of HCC PDX cells as organoids with preserved viability, molecular features, and heterogeneity.

Electroacupuncture facilitates the integration of a grafted TrkC-modified mesenchymal stem cell-derived neural network into transected spinal cord in rats via increasing neurotrophin-3.

AimsThis study was aimed to investigate whether electroacupuncture (EA) would increase the secretion of neurotrophin‐3 (NT‐3) from injured spinal cord tissue, and, if so, whether the increased NT‐3 would promote the survival, differentiation, and migration of grafted tyrosine kinase C (TrkC)‐modified mesenchymal stem cell (MSC)‐derived neural network cells. We next sought to determine if the latter would integrate with the host spinal cord neural circuit to improve the neurological function of injured spinal cord.MethodsAfter NT‐3‐modified Schwann cells (SCs) and TrkC‐modified MSCs were co‐cultured in a gelatin sponge scaffold for 14 days, the MSCs differentiated into neuron‐like cells that formed a MSC‐derived neural network (MN) implant. On this basis, we combined the MN implantation with EA in a rat model of spinal cord injury (SCI) and performed immunohistochemical staining, neural tracing, electrophysiology, and behavioral testing after 8 weeks.ResultsElectroacupuncture application enhanced the production of endogenous NT‐3 in damaged spinal cord tissues. The increase in local NT‐3 production promoted the survival, migration, and maintenance of the grafted MN, which expressed NT‐3 high‐affinity TrkC. The combination of MN implantation and EA application improved cortical motor‐evoked potential relay and facilitated the locomotor performance of the paralyzed hindlimb compared with those of controls. These results suggest that the MN was better integrated into the host spinal cord neural network after EA treatment compared with control treatment.ConclusionsElectroacupuncture as an adjuvant therapy for TrkC‐modified MSC‐derived MN, acted by increasing the local production of NT‐3, which accelerated neural network reconstruction and restoration of spinal cord function following SCI.

Polydopamine-modified collagen sponge scaffold as a novel dermal regeneration template with sustained release of platelet-rich plasma to accelerate skin repair: A one-step strategy

Although employed to release growth factors (GFs) for regenerative medicine, platelet-rich plasma (PRP) has been hindered by issues like burst effect. Based on collagen sponge scaffolds (CSSs) modified with polydopamine (pDA), a novel dermal regeneration template (DRT) was designed. However, whether it could efficiently deliver PRP and even foster wound healing remained unclear. In this work, after PRP was prepared and pDA-modified CSSs (pDA-CSSs) were fabricated, microscopic observation, GFs release assay and in-vitro biological evaluations of pDA-CSSs with PRP (pDA-CSS@PRP) were performed, followed by BALA-C/nu mice full-thickness skin defects implanted with pDA-CSS@PRP covered by grafted skins (termed as a One-step strategy). As a result, scanning electron microscope demonstrated more immobilized platelets on pDA-CSS′ surface with GFs’ controlled release via enzyme-linked immunosorbent assay, compared with CSSs. In line with enhanced in-vitro proliferation, adhesion and migration of keratinocytes & endothelial cells, pDA-CSS@PRP were histologically revealed to accelerate wound healing with less scar via rapid angiogenesis, arrangement of more mature collagen, guiding cells to spread, etc. In conclusion, pDA-CSSs have potential to serve as a novel DRT capable of delivering PRP, which may foster full-thickness skin defect healing by means of a One-step strategy.

Proliferation and tenogenic differentiation of bone marrow mesenchymal stem cells in a porous collagen sponge scaffold.

BACKGROUNDCollagen is one of the most commonly used natural biomaterials for tendon tissue engineering. One of the possible practical ways to further enhance tendon repair is to combine a porous collagen sponge scaffold with a suitable growth factor or cytokine that has an inherent ability to promote the recruitment, proliferation, and tenogenic differentiation of cells. However, there is an incomplete understanding of which growth factors are sufficient and optimal for the tenogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) in a collagen sponge-based 3D culture system.AIMTo identify one or more ideal growth factors that benefit the proliferation and tenogenic differentiation of rat BMSCs in a porous collagen sponge scaffold.METHODSWe constructed a 3D culture system based on a type I collagen sponge scaffold. The surface topography of the collagen sponge scaffold was observed by scanning electron microscopy. Primary BMSCs were isolated from Sprague-Dawley rats. Cell survival on the surfaces of the scaffolds with different growth factors was assessed by live/dead assay and CCK-8 assay. The mRNA and protein expression levels were confirmed by quantitative real-time polymerase chain reaction and Western blot, respectively. The deposited collagen was assessed by Sirius Red staining.RESULTSTransforming growth factor β1 (TGF-β1) showed great promise in the tenogenic differentiation of BMSCs compared to growth differentiation factor 7 (GDF-7) and insulin-like growth factor 1 (IGF-1) in both the 2D and 3D cultures, and the 3D culture enhanced the differentiation of BMSCs into tenocytes well beyond the level of induction in the 2D culture after TGF-β1 treatment. In the 2D culture, the proliferation of the BMSCs showed no significant changes compared to the control group after TGF-β1, IGF-1, or GDF-7 treatment. However, TGF-β1 and GDF-7 could increase the cell proliferation in the 3D culture. Strangely, we also found more dead cells in the BMSC-collagen sponge constructs that were treated with TGF-β1. Moreover, TGF-β1 promoted more collagen deposition in both the 2D and 3D cultures.CONCLUSIONCollagen sponge-based 3D culture with TGF-β1 enhances the responsiveness of the proliferation and tenogenic differentiation of rat BMSCs.

Effect of nano-biomaterials silk-collagen sponge scaffold on the tendon and ligament healing of patients with anterior cruciate ligament injuries

With the rapid development of nanotechnology, the application of nanomaterials is more and more extensive, and the contact between humans, animals and plants and nanomaterials is inevitable. Anterior cruciate ligament (ACL) is an important intra-articular ligament of the knee joint, which plays a very significant role in the normal movement and functional stability of the knee joint. ACL is generally difficult to heal after injury and the main treatment method currently is use auto-graft or allograft and synthetic materials for ACL reconstruction, but there exist problems such as large demand but limited sources. Nanotechnology development provides new ideas and approaches for ACL reconstruction. This technology inoculates certain cells from autologous tissues into scaffold materials, and then implants the grown cell scaffold complex into defect or injury sites for completing the tissue or organ defect repair and functional reconstruction. On the basis of summarising and analysing previous research results, this paper selected silk and collagen sponges as experimental materials to prepare nano-biological scaffolds, then observed the surface structure of the prepared scaffolds under scanning electron microscope and conducted histological analysis and biomechanical testing, and finally applied this nano-silk-collagen sponge biomaterial scaffold (NNSCSBS) to the tendon ligament repair surgery of patients with ACL injury. The results showed that collagen fills fibrous spaces with relatively uniform distribution after NSCSBS hybridisation, and the NSCSBS cultured in vitro had more abundant skin fibroblasts growth; the NSCSBS had the porosity of (77.63 ± 1.82)%, the moisture of (78.24 ± 1.19)%, the maximum load of (122.48 ± 12.66) N, the stiffness of (26.07 ± 2.58) N/mm without statistically significant differences (P > 0.05); postoperative ACL's bone mineral density and collagen fibre composition both increased; the graft tendon was surrounded by new bone tissue, and the tendon and bone were connected by fibrous collagen with narrower interface gap and more mature new bone tissue. Therefore, the NSCSBS can provide mechanical support with silk scaffolds as the core, increase the scaffold's three-dimensional space with composite collagen as bio-component, promote more cell adhesion and improve biocompatibility of nano-biomaterial scaffold, and better repair ligament-osseous junction to form a bionic structure, having a good application prospect.

Sodium alginate-based composites as a collagen substitute for skin bioengineering

The skin is a combination of two different types of tissue—epithelial and connective (mesenchymal). The outer protective layer of the skin, the epidermis, consists of multiple layers of keratinocytes residing on the basement membrane that separates them from the underlying dermis, which consists of a well-vascularized fibrous extracellular matrix seeded mainly by fibroblasts and mesenchymal stromal cells. These skin features suggest that the development of a fibroblast-friendly porous scaffold covered with a flat dense sheath mimicking the basement membrane, and sufficient to support keratinocyte attachment, would be a reasonable approach in the generation of clinically-relevant skin substitutes useful for reconstructive dermatology and burn treatment. Therefore, we developed a procedure to obtain biocompatible composite bilayer scaffolds comprising a spongy dermis-like body (supporting vascularization and appropriate fibroblast and multipotent stromal cell activity) fused with a film-like cover (supporting keratinocyte attachment, growth and differentiation). The sodium alginate (SA), an algae-derived biopolymer, has been used as a base component for these scaffolds while collagen (CL) and fibrinogen (FG) were used as minor additives in variable concentrations. The slow rates of composite SA-based scaffold biodegradation were achieved by using Ba2+ as cross-linking cations. By manipulating the SA/CL/FG ratio we managed to obtain sponge scaffolds with highly interconnected porous structures, with an average pore size ranging from 60 to 300 μm, and sufficient tensile strength (3.12–5.26 MPa). The scaffolds biocompatibility with the major human skin cell types was confirmed by seeding the scaffold sponge compartment with primary skin fibroblasts and subcutaneous adipose-derived stromal cells while the film side biocompatibility was tested using primary human keratinocytes. The obtained results have shown that bilayer alginate-based scaffolds have biological and mechanical properties comparable with CL scaffolds but surpass them in cost efficiency and vascularization ability in the subcutaneous implantation model in laboratory mice.

Loofah-based microalgae and cyanobacteria biocomposites for intensifying carbon dioxide capture

Abstract Microalgae and cyanobacteria have been evaluated for biological CO2 capture from flue gases for over 40 years; however, commercial open ponds and photobioreactors suffer many drawbacks including a slow rate of CO2 capture and high water usage. We evaluate an intensified 3D cell immobilisation approach with a small water demand, by coating latex binders onto defined surface area (947 m2 m−3) and void space (81.78 ± 4.41 %) loofah sponge scaffolds, forming porous 3D biocomposites with three microalgae species; freshwater Chlorella vulgaris, marine Dunaliella salina and Nannochloropsis oculata, and two strains of freshwater Synechococcus elongatus cyanobacteria. Binder toxicity and adhesion screening protocols were established ahead of eight weeks semi-batch and six weeks continuous CO2 fixation trials. Acrylic and polyurethane binders were effective for microalgae, and bio-based (Replebin®) binders were suited for cyanobacteria. The highest average net CO2 fixation rates from each species were 0.17 ± 0.01, 0.25 ± 0.01, 0.12 ± 0.01, 0.68 ± 0.18 and 0.93 ± 0.30 g CO2 g-1biomass d-1 for C. vulgaris, D. salina, N. oculata, S. elongatus PCC 7942 and S. elongatus CCAP 1479/1A respectively. This equates to predicted CO2 capture from scaled systems of up to 340.11 ± 110 tCO2 t-1biomass yr-1. Analysis of the kinetics of CO2 absorbtion and SEM imaging suggests that the cells were embedded within a polymer film that covered the scaffold. Biocomposites continuously fed with 5% CO2 had high lipid contents approaching 70 % dry weight. This biocomposite approach shows promise to intensify biological CO2 capture and possible application in bioenergy with carbon capture and storage (BECCS).

3D Structure and Mechanics of Silk Sponge Scaffolds Is Governed by Larger Pore Sizes

Three-dimensional scaffolds play an essential role in tissue engineering. Although essential, the tunability of the 3D scaffolds mechanical and transport properties remains a challenge. In this work, we present new approaches to advance the field. First, we applied our progressive pH acidification to mimic the natural silk gelation process before ice-templating (−20 and −80°C); second, we fitted the mechanical properties using a connectivity model; third, we fitted the scaffolds mechanical relaxation to understand the transport properties; and fourth we used micro-CT to correlate the process parameters to the scaffolds' performances. Our results suggested that the free shrinkage of the scaffolds determined their final properties. We found, however, that the porosity (above 90%) was anisotropic, similarly the tortuosity (between 1 and 1.3). We identified two major pore dimensions, the first one between 10 and 20 μm, and the second between 50 and 130 μm. Mechanically, our model suggested that the bulk modulus captured the elastic contribution and was controlled predominantly by the silk concentration. We tentatively associated the fractional modulus 1 to the collapse of the larger pores structures and was controlled mostly by the process temperature. We assigned the slow relaxation to the transport of fluid in the silk sponge scaffolds; and the fast relaxation with a viscoelastic relaxation. The silk concentration and process temperatures did not influence the latter. Overall, our use of the tomography, mechanical test, and detailed statistical analysis provides inroads into the interplay between process parameters (silk concentration and process temperature) and the multiple responses of the silk sponge scaffolds. The development of a new mechanical fitting for the compression test helped capture simply the different failure modes in the sponge scaffolds as well as correlating those events to relaxation and eventually transport properties. (Less)

Epithelial differentiation of human adipose-derived stem cells (hASCs) undergoing three-dimensional (3D) cultivation with collagen sponge scaffold (CSS) via an indirect co-culture strategy

BackgroundThree-dimensional (3D) cultivation with biomaterials was proposed to facilitate stem cell epithelial differentiation for wound healing. However, whether human adipose-derived stem cells (hASCs) on collagen sponge scaffold (CSS) better differentiate to keratinocytes remains unclear.Methods3D cultivation with CSS on hASC epidermal differentiation co-cultured with HaCaT cells at air-liquid interface (ALI) was compared with two-dimensional (2D) form and cultivation without “co-culture” or “ALI.” Cellular morphology, cell adhesion, and growth condition were evaluated, followed by the protein and gene expression of keratin 14 (K14, keratinocyte specific marker).ResultsTypical cobblestone morphology of keratinocytes was remarkably observed in co-cultured hASCs at ALI, but those seeded on the CSS exhibited more keratinocyte-like cells under an invert microscope and scanning electron microscope. Desired cell adhesion and proliferation were confirmed in 3D differentiation groups by rhodamine-labeled phalloidin staining, consistent with H&E staining. Compared with those cultured in 2D culture system or without “ALI,” immunofluorescence staining and gene expression analysis revealed hASCs co-cultured over CSS expressed K14 at higher levels at day 15.ConclusionsCSS is positive to promote epithelial differentiation of hASCs, which will foster a deeper understanding of artificial dermis in skin wound healing and regeneration.

Strontium-substituted biphasic calcium phosphate scaffold for orthopedic applications

Strontium ion-substituted calcium phosphate-based ceramic scaffolds enhance osteogenesis. The objective of the present study was to optimize the strontium hydroxyapatite (Sr-HA) and beta tricalcium phosphate (β-TCP) ratio in the fabricated scaffolds to enhance their mechanical strength and bioactivity with controlled biodegradability. Porous polyurethane sponge scaffolds containing Sr-HA and β-TCP in varying concentration were developed by dipping 3D sponge pieces into a slurry containing 10% gelatin, proper concentration of biphasic calcium phosphate (BCP) and 3% poly vinyl alcohol. Four different samples [Sr-BCP, Sr-BCP (20/80), Sr-BCP (30/70), Sr-BCP (40/60)] were prepared and were characterized for biodegradability, water uptake capability and cytotoxicity using various techniques. Pure, crystalline, cytocompatible Sr-BCP Scaffolds possessing both micropores and macropores with porosity greater than 80% and water uptake capability above 100% were obtained. Thus, the effective substitution of Sr-HA and β-TCP in varying proportion makes the composite scaffold a distinctive material of bone tissue engineering.

Comparison of Regenerative Effects of Transplanting Three-Dimensional Longitudinal Scaffold Loaded-Human Mesenchymal Stem Cells and Human Neural Stem Cells on Spinal Cord Completely Transected Rats.

Stem cell-based therapy has been considered as a potential treatment to restore spinal cord injury (SCI) through reconstructing neural networks and providing a favorable microenvironment for neuronal survival, differentiation, and axonal outgrowth. Biomaterial scaffolds can promote cell attachment and survival, neuronal differentiation, and axonal outgrowth; therefore, they were used to combine with stem cells for implantation in SCI treatment. In addition, a longitudinal scaffold can guide regenerated axons with orientated growth and axial extension. Both human umbilical cord-derived mesenchymal stem cells (hMSCs) and human fetal spinal cord-derived neural stem cells (hNSCs) have been applied in clinical trials worldwide. To our knowledge, a parallel comparison of the therapeutic effects of hMSC and hNSC implantations has not been conducted. Hence, in this study, we grafted hMSCs or hNSCs seeded on longitudinal collagen sponge scaffolds into rats with completely transected SCI to examine differences in SCI repair. Both hMSCs and hNSCs had equivalent effects on reducing glial scar formation around the lesion gap. More neuronal class III β-tubulin-positive neurons and neurofilament-positive nerve fibers were found in the lesion cavity after hNSC implantation. In addition, hNSCs had better capabilities to improve motor function, attenuate inflammation, and promote cell survival than hMSCs. These encouraging results provide a clinical basis for future stem cell-based SCI therapies.

HGF Gene Delivering Alginate/Galactosylated Chitosan Sponge Scaffold for Three-Dimensional Coculture of Hepatocytes/3T3 Cells.

Gene delivery from tissue engineering scaffold is a novel strategy in regulating long-term growth and function of cells in vitro culture. In this study, a hepatocyte growth factor plasmid/polyetherimide (pHGF/PEI) polyplex delivering alginate (AL)/galactosylated chitosan (GC) (pHGF/PEI-AL/GC) sponge scaffold was prepared for the in vitro coculture of hepatocytes/3T3 cells. The pHGF/PEI polyplex released for 6 days in the sponge scaffold with weight ratio of AL/GC being 3:1 and fixed amount of pHGF being 40 μg (24-well scaffold). In addition, the 3T3 cells culturing in the pHGF/PEI-AL/GC sponge scaffold could be continually transfected and expressed the exogenous HGF for 6 days. Furthermore, the albumin secretion and urea synthesis of hepatocytes were significantly enhanced when cocultured with 3T3 cells in the pHGF/PEI-AL/GC sponge scaffold compared with that in the AL/GC sponge without pHGF. In summary, the preparation of AL/GC sponge scaffold delivering pHGF/PEI polyplex is a critical significance for maintaining the long-term survival and function of primary hepatocytes in vitro.

Aligned collagen scaffold combination with human spinal cord-derived neural stem cells to improve spinal cord injury repair.

Neural stem/progenitor cell (NSPC)-based spinal cord injury (SCI) therapy is expected to bridge the lesion site by transplanting exogenous NSPCs for replacement of lost cells. The transplanted NSPCs produce a microenvironment conducive to neuronal regeneration, and ultimately, functional recovery. Although both human fetal brain- and spinal cord- derived NSPCs (hbNSPCs and hscNSPCs, respectively) have been used for SCI repair, it remains unclear whether hscNSPCs are a more appropriate stem cell source for transplantation than hbNSPCs. Therefore, in this study, we transplanted hbNSPCs or hscNSPCs into rats with complete transection SCI to monitor their differences in SCI treatment. An aligned collagen sponge scaffold (ACSS) was used here for cell retention. Aligned biomaterial scaffolds provide a support platform and favorable morphology for cell growth and differentiation, and guide axial axonal extension. The ACSS fabricated by our group has been previously reported to improve spinal cord repair by promoting neuronal regeneration and remyelination. Compared with the hbNSPC-ACSS, the hscNSPC-ACSS effectively promoted long-term cell survival and neuronal differentiation and improved the SCI microenvironment by reducing inflammation and glial scar formation. Furthermore, the transplanted hscNSPC-ACSS improved recovery of locomotor functions. Therefore, hscNSPCs appear to be a superior cell source to hbNSPCs for SCI cell therapy with greater potential clinical applications.

Therapeutic Potential of Human iPS Cell-Derived Endothelial and Mural Cells Incorporated with Gelatin Sponge Scaffold in a Murine Hindlimb Ischemia Model

Introduction - To standardize stem cell-based therapeutic angiogenesis for peripheral artery disease, a transplantation strategy to achieve efficient and sustainable therapeutic effect is required. In this study, we have investigated therapeutic effects of human induced pluripotent stem cell (hiPSC)-derived endothelial cells (ECs) and vascular mural cells (MCs) incorporated with gelatin sponge (GS) scaffold in a murine hindlimb ischemia model.

A comparative study of two porous sponge scaffolds prepared by collagen derived from porcine skin and fish scales as burn wound dressings in a rabbit model.

Collagen is widely used in biomedical applications due to its outstanding properties. In this study, highly porous sponge scaffolds were developed by using porcine skin-derived collagen (PSC) and fish scale-derived collagen (FSC), respectively. The morphology and composition of these PSC and FSC scaffolds were compared. The water uptake ratio of FSC scaffolds reached 47.8, which is 1.7 times of PSC scaffolds. The water vapour transmission rates (WVTR) of PSC and FSC scaffolds were 952.6 ± 55.5 and 1090.9 ± 77.1 g/m2/day, which could produce a moist healing environment for wounds. Both scaffolds show non-toxicity to L929 fibroblast cells. The burn wound healing efficiency of these two scaffolds was examined in vivo using rabbits. No scars around the wounds were observed after applying PSC and SFC scaffolds. Histopathological studies reveal that the wound treated with PSC and FSC scaffolds showed much better wound recovery than gauze and vaseline gauze groups. It was suggested that FSC scaffolds have great potential as same as PSC to be used as burn wound dressing materials.

Preparation and Statistical Characterization of Tunable Porous Sponge Scaffolds using UV Cross-linking of Methacrylate-Modified Silk Fibroin.

Silk fibroin sponges have been widely studied and reported in literature for tissue engineering applications. Several fabrication methods have been proposed during the years to cover most of the demands in terms of properties, which should be adapted to the considered tissue. Most of these procedures are based on the secondary structure transition of the protein to the stable β crystalline form. This transition, known as physical cross-linking, makes the sponge resistant to dissolution in water, and, in general, increases the sponge stiffness. In our work, we propose an alternative method to ensure the stability of the sponge based on chemical cross-linking of a methacrylated version of silk fibroin (Sil-MA) obtained via chemical modification. The Sil-MA water solution with the addition of a photoinitiator (LAP) allows the opening, under UV radiation, of a double carbon-carbon bond and radical polymerization. The incorporation of air bubbles (that serves as a template for the pores) was accomplished by a mixer; then, the foam was stabilized under UV light and the excess water was removed by freeze-drying. Because of the cytotoxicity of the photoinitiator (found when used at a high concentration), an additional washing step in water has been introduced to eliminate the residues and improve the cells' viability. Fourier transform infrared (FTIR) analysis confirmed the functionalization of the protein. To evaluate the effect of the composition on the sponge properties, a 23 full factorial design of the experiment has been adopted. FTIR analysis revealed that the sponge composition did not affect the protein's secondary structure. The analysis of images obtained by SEM allowed some statistical measures of the porosity curves to be studied and modeled. The same modeling procedure was applied to the dissolution test in a simulated body fluid, to the water absorption, and to the cell viability (tested by the MTT and LDH assays). An empirical model for each property was built, showing how by changing the composition it is possible to tune the sponge properties.

Evaluation of Small Molecule Drug Uptake in Patient-Derived Prostate Cancer Explants by Mass Spectrometry

Patient-derived explant (PDE) culture of solid tumors is increasingly being applied to preclinical evaluation of novel therapeutics and for biomarker discovery. In this technique, treatments are added to culture medium and penetrate the tissue via a gelatin sponge scaffold. However, the penetration profile and final concentrations of small molecule drugs achieved have not been determined to date. Here, we determined the extent of absorption of the clinical androgen receptor antagonist, enzalutamide, into prostate PDEs, using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and matrix-assisted laser/desorption ionisation (MALDI) mass spectrometry imaging (MSI). In a cohort of 11 PDE tissues from eight individual patients, LC-MS/MS quantification of PDE homogenates confirmed enzalutamide (10 µM) uptake by all PDEs, which reached maximal average tissue concentration of 0.24–0.50 ng/µg protein after 48 h culture. Time dependent uptake of enzalutamide (50 µM) in PDEs was visualized using MALDI MSI over 24–48 h, with complete penetration throughout tissues evident by 6 h of culture. Drug signal intensity was not homogeneous throughout the tissues but had areas of markedly high signal that corresponded to drug target (androgen receptor)-rich epithelial regions of tissue. In conclusion, application of MS-based drug quantification and visualization in PDEs, and potentially other 3-dimensional model systems, can provide a more robust basis for experimental study design and interpretation of pharmacodynamic data.