Cell Delivery Carrier Research Articles

ROS responsive conductive microspheres loaded with salvianolic acid B as adipose derived stem cell carriers for acute myocardial infarction treatment

Stem cell therapy is currently the most promising strategy for the treatment of myocardial infarction. However, the development of injectable cell carriers that can scavenge reactive oxygen species (ROS) in the infarct zone to improve transplanted cell survival remains a challenge. Here, we developed a ROS responsive conductive microsphere based on chitosan (CS) and dextran (DEX) with 4-formylphenylboronic acid (4-FPBA) as a cross-linking agent and the addition of graphite oxide (GO) and the anti-inflammatory agent salvianolic acid B (SalB), as a cell delivery carrier for myocardial infarction. These microspheres were crosslinked by dual dynamic networks of Schiff base and phenylborate bonds. The relationship between CS concentration and microsphere particle size, as well as the biocompatibility, ROS responsiveness, anti-inflammatory properties, and effects on myogenic differentiation of H9C2 cells were fully investigated. The microspheres exhibit good biocompatibility, proliferation promoting, differentiation promoting, antioxidant, and anti-inflammatory properties. When applied to mice myocardial infarction models, the ROS responsive conductive microspheres loaded with SalB and adipose derived stem cells (ADSC) exhibited excellent in vivo repair ability. In addition, they reduced myocardial fibrosis and promoted ventricular wall regeneration by promoting the expression of Connexin 43 (Cx43) and CD31, ultimately reshaping the infarcted myocardium, suggesting their great potential as cell delivery carriers for myocardial infarction treatment.

Versatile cell cultivation on injectable poly(butylene adipate-co-terephthalate) microcarriers: Impact of surface properties across different cell types.

Injectable cell therapies offer several advantages compared with traditional open surgery, including less trauma to the patient, shorter recovery time, and lower risk of infection. However, a significant problem is the difficulty in developing effective cell delivery carriers that are cyto-compatible and maintain cell viability both during and after injection. In the presented study, it was aimed to develop poly(butylene adipate-co-terephthalate) (PBAT) microcarriers using the emulsion preparation-solvent evaporation technique. The optimized diameter of the PBAT microcarriers was determined as 104 ± 15 μm at 700 rpm and there would be no blockage after injection due to the nonswelling feature of microcarriers. Furthermore, the cellular activities of PBAT microcarriers were evaluated in static culture for 7 days using L929 mouse fibroblasts, MC3T3-E1 mouse pre-osteoblasts, and rat adipose-derived mesenchymal cells (AdMSCs). 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide results and Sscanning electron microscope images showed that PBAT microcarriers increased the adhesion and proliferation properties of pre-osteoblasts and stem cells, while L929 fibroblasts formed aggregates by adhering to certain regions of the microcarrier surface and did not spread on the surface. These results emphasize that PBAT microcarriers can be used as injectable carriers, especially in stem cell therapies, but their surface properties need to be modified for some cells.

Enhanced fibrocartilage regeneration at the tendon-bone interface injury through extracellular matrix hydrogel laden with bFGF-overexpressing human urine-derived stem cells

The tendon-bone interface (TBI) is crucial in the transfer of mechanical loads; however, it is susceptible to injuries that frequently result in healing via fibrous scar tissue formation. Consequently, regeneration of the fibrocartilaginous zone has become a pivotal area subject. At present, the use of stem cells represents a notably promising approach for TBI treatment. Especially, human urine-derived stem cells (hUSCs) present a practical option for cell-based therapies. Nevertheless, the chondrogenic differentiation potential of hUSCs is limited. To address this, basic fibroblast growth factor (bFGF) was transinfected into hUSCs to bolster their differentiation capacity and facilitate the formation of fibrocartilage in the target area. Additionally, the local immune microenvironment dramatically influences TBI healing, with macrophages playing a vital role. Effective healing relies on the phenotype transition of macrophages, with an imbalance often leading to insufficient regeneration and scar tissue formation. Innovations in biomaterials have provided new avenues for TBI repair, such as the porcine small intestinal submucosa (SIS) hydrogel developed in our prior research. In addition to serving as a carrier for stem cell delivery, the hydrogel’s bioactive components support tissue repair and immune regulation. In the present study, SIS hydrogel loaded with hUSCs that overexpress bFGF was used for the treatment of TBI injury, which is expected to correct inflammatory response imbalances, and promote macrophage polarization towards healing phenotypes, creating a favorable immune microenvironment. The combined effects of bFGF and the optimized immune setting are anticipated to enhance hUSCs’ chondrogenic potential, aiding in the functional restoration of TBI injuries.

Gelatin-Based Scaffolds with Carrageenan and Chitosan for Soft Tissue Regeneration.

Motivated by the enormous potential of hydrogels in regenerative medicine, new biocompatible gelatin-based hybrid hydrogels were developed through a green process using poly(ethylene glycol) diglycidyl ether as a cross-linking agent, adding carrageenan and chitosan polysaccharides to the network to better mimic the hybrid composition of native extracellular matrix. Overall, the hydrogels show suitable structural stability, high porosity and pore interconnectivity, good swellability, and finally, biocompatibility. Their mechanical behavior, investigated by tensile and compression tests, appears to be characterized by nonlinear elasticity with high compliance values, fast stress-relaxation, and good strain reversibility with no sign of mechanical failure for compressive loading-unloading cycles at relatively high deformation levels of 50%. Degradation tests confirm the hydrogel bioresorbability by gradual hydrolysis, during which the structural integrity of both materials is maintained, while their mechanical behavior becomes more and more compliant. Human Umbilical Cord-derived Mesenchymal Stem Cells (hUC-MSCs) were used to test the hydrogels as potential carriers for cell delivery in tissue engineering. hUC-MSCs cultured inside the hydrogels show a homogenous distribution and maintain their growth and viability for at least 21 days of culture, with an increasing proliferation trend. Hence, this study contributes to a further understanding of the potential use of hybrid hydrogels and hUC-MSCs for a wide range of biomedical applications, particularly in soft tissue engineering.

Hydrogel Encapsulation Techniques and Its Clinical Applications in Drug Delivery and Regenerative Medicine: A Systematic Review.

Hydrogel encapsulation is a promising carrier for cell and drug delivery due to its ability to protect the encapsulated entities from harsh physiological conditions and enhance their therapeutic efficacy and bioavailability. However, there is not yet consensus on the optimal hydrogel type, encapsulation method, and clinical application. Therefore, a systematic review of hydrogel encapsulation techniques and their potential for clinical application is needed to provide a comprehensive and up-to-date overview. In this systematic review, we searched electronic databases for articles published between 2008 and 2023 that described the encapsulation of cells or drug molecules within hydrogels. Herein, we identified 9 relevant studies that met the inclusion and exclusion criteria of our study. Our analysis revealed that the physicochemical properties of the hydrogel, such as its porosity, swelling behavior, and degradation rate, play a critical role in the encapsulation of cells or drug molecules. Furthermore, the encapsulation method, including physical, chemical, or biological methods, can affect the encapsulated entities' stability, bioavailability, and therapeutic efficacy. Challenges of hydrogel encapsulation include poor control over the release of encapsulated entities, limited shelf life, and potential immune responses. Future directions of hydrogel encapsulation include the development of novel hydrogel and encapsulation methods and the integration of hydrogel encapsulation with other technologies, such as 3D printing and gene editing. In conclusion, this review is useful for researchers, clinicians, and policymakers who are interested in this field of drug delivery and regenerative medicine that can serve as a guide for the future development of novel technologies that can be applied into clinical practice.

Pluronic F127 composite hydrogel for the repair of contraction suppressed full-thickness skin wounds in a rabbit model

Hydrogels are commonly used as carriers for cell delivery due to their similarities to the extracellular matrix. A contraction-suppressed full-thickness wound model was used to evaluate the therapeutic potential of Pluronic F127 (PF127) hydrogel loaded with adipose-derived stromal vascular fraction (AdSVF), mesenchymal stem cells (AdMSC), and conditioned media (AdMSC-CM) for the repair of wounds in a rabbit model. The experimental study was conducted on forty-eight healthy adult New Zealand white rabbits randomly divided into eight groups with six animals each and treated with AdSVF, AdMSC, and AdMSC-CM as an injectable or topical preparation. The healing potential of different adipose-derived cell-based and cell-free therapeutics was evaluated based on percentage wound healing, period of epithelialization, epidermal thickness, scar evaluation, histopathology analysis, histochemical evaluation, immunohistochemistry (collagen type I), and hydroxyproline assay by comparing with the positive and negative control. Collagen density analysis using different staining methods, immunohistochemistry, and hydroxyproline assay consistently showed that delivering AdMSC and AdMSC-CM in PF127 hydrogel enhanced epithelialization, collagen production, and organization, contributing to improved tissue strength and quality. Even though allogeneic AdSVF was found to promote wound healing in rabbits, it has a lower potential than AdMSC and AdMSC-CM. The wound healing potential of AdMSC and AdMSC-CM was enhanced when loaded in PF127 hydrogel and applied topically. Even though wounds treated with AdMSC outperformed AdMSC-CM, a significant difference in the healing quality was not observed in most instances, indicating almost similar therapeutic potential. The findings indicate that the wound healing potential of AdMSC and AdMSC-CM was enhanced when loaded in PF127 hydrogel and applied topically. These treatments promoted collagen production, tissue organization, and epidermal regeneration, ultimately improving overall healing outcomes.

Injectable microcapillary network hydrogels engineered by liquid-liquid phase separation for stem cell transplantation

Injectable hydrogels are promising carriers for cell delivery in regenerative medicine. However, injectable hydrogels composed of crosslinked polymer networks are often non-microporous and prevent biological communication with host tissues through signals, nutrients, oxygen, and cells, thereby limiting graft survival and tissue integration. Here we report injectable hydrogels with liquid-liquid phase separation-induced microcapillary networks (μCN) as stem cell-delivering scaffolds. The molecular modification of gelatin with hydrogen bonding moieties induced liquid-liquid phase separation when mixed with unmodified gelatin to form μCN structures in the hydrogels. Through spatiotemporally controlled covalent crosslinking and dissolution processes, porous μCN structures were formed in the hydrogels, which can enhance mass transport and cellular activity. The encapsulation of cells with injectable μCN hydrogels improved cellular spreading, migration, and proliferation. Transplantation of mesenchymal stem cells with injectable μCN hydrogels enhanced graft survival and recovered hindlimb ischemia by enhancing material-tissue communication with biological signals and cells through μCN. This facile approach may serve as an advanced scaffold for improving stem cell transplantation therapies in regenerative medicine.

Application of Hydrogels in Cardiac Regeneration.

Myocardial infarction (MI) is a leading cause of death globally. Due to limited cardiac regeneration, infarcted myocardial tissue is gradually replaced by cardiac fibrosis, causing cardiac dysfunction, arrhythmia, aneurysm, free wall rupture, and sudden cardiac death. Thus, the development of effective methods to promote cardiac regeneration is extremely important for MI treatment. In recent years, hydrogels have shown promise in various methods for cardiac regeneration. Hydrogels can be divided into natural and synthetic types. Different hydrogels have different features and can be cross-linked in various ways. Hydrogels are low in toxicity and highly stable. Since they have good biocompatibility, biodegradability, and transformability, moderate mechanical properties, and proper elasticity, hydrogels are promising biomaterials for promoting cardiac regeneration. They can be used not only as scaffolds for migration of stem cells, but also as ideal carriers for delivery of drugs, genetic materials, stem cells, growth factors, cytokines, and small molecules. In this review, the application of hydrogels in cardiac regeneration during or post-MI is discussed in detail. Hydrogels open a promising new area in cardiac regeneration for treating MI.

Short Peptide Nanofiber Biomaterials Ameliorate Local Hemostatic Capacity of Surgical Materials and Intraoperative Hemostatic Applications in Clinics.

Short designer self-assembling peptide (dSAP) biomaterials are a new addition to hemostat group. It may provide diverse and robust toolboxes for surgeon to integrate wound microenvironment with much safer and stronger hemostatic capacity than conventional materials and hemostatic agents. Especially in noncompressible torso hemorrhage (NCTH), diffuse mucosal surface bleeding, and internal medical bleeding (IMB), etal., with respect to the optimal hemostatic formulation, dSAP biomaterials are the ingenious nanofiber alternatives to make bioactive neural scaffold, nasal packing, large mucosal surface coverage in gastrointestinal surgery (esophagus, gastric lesion, duodenum, and lower digestive tract), epicardiac cell delivery carrier, transparent matrix barrier, etal. Herein, in multiple surgical specialties, dSAP biomaterials-based nano hemostats achieve safe, effective and immediate hemostasis, facile wound healing, and potentially reduce the risks in delayed bleeding, rebleeding, postoperative bleeding or related complications. The biosafety in vivo, bleeding indications, tissue-sealing quality, surgical feasibility, and local usability are addressed comprehensively and sequentially and pursued to develop useful surgical techniques with better hemostatic performance. This article provides the state of art and all-round advancements of nano hemostatic approaches in surgery. Relevant critical insights will inspire exciting investigations on peptide nanotechnology, next-generation biomaterials, and better promising prospects in clinics. This article is protected by copyright. All rights reserved.

Conductive self-healing biodegradable hydrogel based on hyaluronic acid-grafted-polyaniline as cell recruitment niches and cell delivery carrier for myogenic differentiation and skeletal muscle regeneration

Scaffold is one of the most important roles in skeletal muscle tissue engineering. Being capable of mimicking extracellular matrix components, having electrical conductivity, and recruiting cells proactively to meet the cell-free requests are the proper characteristics of tissue engineering scaffolds. In this work, a series of leucine (Leu) loaded self-healing conductive hydrogels based on aminated hyaluronic acid-graft-polyaniline (AHA-PANI) and oxidized hyaluronic (OHA) were prepared for skeletal muscle tissue engineering. Leu can promote skeletal myogenesis and hydrogel can provide a suitable growth environment for cells. They have self-healing properties, antioxidant activity, suitable modulus, good electrical conductivity, high porosity, and proper swelling ratio. Additionally, these hydrogels have good cytocompatibility and can provide a 3D culture environment for C2C12 and hADSC cells. The Leu-loaded hydrogel has recruiting ability of cells and can promote myogenic differentiation of C2C12 cells. Besides, these hydrogels enable sustained cell delivery, and have good in vivo degradability and exhibited promoting effect on skeletal muscle regeneration in the rat tibialis anterior muscle defect model with reduced post-repair inflammatory factor expression and enhanced myogenic differentiation-related gene expression. All the results indicated that these conductive hydrogels as self-healing cell recruitment niches are excellent biomaterial for the treatment of volumetric muscle loss injury.

Engineering thixotropic supramolecular gelatin-based hydrogel as an injectable scaffold for cell transplantation

Despite many efforts focusing on regenerative medicine, there are few clinically-available cell-delivery carriers to improve the efficacy of cell transplantation due to the lack of adequate scaffolds. Herein, we report an injectable scaffold composed of functionalized gelatin for application in cell transplantation. Injectable functionalized gelatin-based hydrogels crosslinked with reversible hydrogen bonding based on supramolecular chemistry were designed. The hydrogel exhibited thixotropy, enabling single syringe injection of cell-encapsulating hydrogels. Highly biocompatible and cell-adhesive hydrogels provide cellular scaffolds that promote cellular adhesion, spreading, and migration. The in vivo degradation study revealed that the hydrogel gradually degraded for seven days, which may lead to prolonged retention of transplanted cells and efficient integration into host tissues. In volumetric muscle loss models of mice, cells were transplanted using hydrogels and proliferated in injured muscle tissues. Thixotropic and injectable hydrogels may serve as cell delivery scaffolds to improve graft survival in regenerative medicine.

Biostimulatory Micro-Fragmented Nanofiber-Hydrogel Composite Improves Mesenchymal Stem Cell Delivery and Soft Tissue Remodeling.

Functional microgels are preferred stem cell carriers due to the ease of delivery through minimally invasive injection and seamless integration with the surrounding host tissue. A biostimulatory nanofiber-hydrogel composite (NHC) has been previously developed through covalently crosslinking a hyaluronic acid hydrogel network with surface-functionalized poly (ε-caprolactone) nanofiber fragments. The NHC mimics the microarchitecture of native soft tissue matrix, showing enhanced cell infiltration, immunomodulation, and proangiogenic properties. Here, injectability of the pre-formed NHC is improved by mechanical fragmentation, making it into micro-fragmented NHC (mfNHC) in a granular gel form as a stem cell carrier to deliver mesenchymal stem cells (MSCs) for soft tissue remodeling. The mfNHC shows a similar storage modulus but a significantly reduced injection force, as compared with the corresponding bulk NHC. When injected subcutaneously in a rat model, mfNHC-MSC constructs initiate an elevated level of host macrophage infiltration, more pro-regenerative polarization, and subsequently, improved angiogenesis and adipogenesis response when compared to mfNHC alone. A similar trend of host cell infiltration and pro-angiogenic response is detected in a swine model with a larger volume injection. These results suggest a strong potential for use of the mfNHC as an injectable carrier for cell delivery and soft tissue remodeling.

Recent Advances on Electroconductive Hydrogels Used in Heart Repair and Regeneration

Myocardial infarction (MI) permanently damages cardiac tissue. Tissue engineering exhibits tremendous potential as a strategy for developing engineered tissue to repair congenital abnormalities in the heart and/or cardiovascular tissue. Electroconductive hydrogels (EHs) are prepared from synthetic or natural biodegradable polymers and conductive components that could partially restore the myocardial/ventricular electromechanical coupling and synchronized heartbeats. Also, EHs are ideal materials for the preparation of cell culture and induction carriers, engineered scaffolds, and patches, as well as cell and gene delivery carriers, all of which aid in tissue formation. Except for a brief introduction to the classification and synthesis of EHs, this review discussed the recent progress and challenges of EHs applied in cardiac repair and regeneration to provide a reference for the further application of EHs in treating cardiovascular diseases. Figure abstract: the EHs categorization and the potential application of heart repair and regeneration in this review.

Development of an Injectable Shear-Thinning Nanocomposite Hydrogel for Cardiac Tissue Engineering.

Bone marrow-derived mesenchymal stem cells (MSCs) offer a promising therapeutic method for cardiac tissue regeneration. However, to monitor the fate of MSCs for tissue repair, a better stem cell delivery carrier is needed. Developing a unique injectable and shear-thinning dual cross-linked hybrid hydrogel for MSC delivery for cardiac tissue engineering is highly desirable. This hydrogel was synthesised using guest: host reaction based on alginate-cyclodextrin (Alg-CD) and adamantane-graphene oxide (Ad-GO). Here, the role of macromere concentration (10 and 12%) on the MSC function is discussed. Our hybrid hydrogels reveal a suitable oxygen pathway required for cell survival. However, this value is strongly dependent on the macromere concentrations, while the hydrogels with 12% macromere concentration (2DC12) significantly enhanced the oxygen permeability value (1.16-fold). Moreover, after two weeks of culture, rat MSCs (rMSCs) encapsulated in Alg-GO hydrogels expressed troponin T (TNT) and GATA4 markers. Noticeably, the 2DC12 hydrogels enhance rMSCs differentiation markers (1.30-times for TNT and 1.21-times for GATA4). Overall, our findings indicate that tuning the hydrogel compositions regulates the fate of encapsulated rMSCs within hydrogels. These outcomes may promote the advancement of new multifunctional platforms that consider the spatial and transient guidelines of undifferentiated cell destiny and capacity even after transplantation for heart tissue regeneration.

Bioactive in situ crosslinkable polymer-peptide hydrogel for cell delivery to the intervertebral disc in a rat model

Degeneration of the intervertebral disc (IVD) is associated with significant biochemical and morphological changes that include a loss of disc height, decreased water content and decreased cellularity. Cell delivery has been widely explored as a strategy to supplement the nucleus pulposus (NP) region of the degenerated IVD in both pre-clinical and clinical trials, using progenitor or primary cell sources. We previously demonstrated an ability for a polymer-peptide hydrogel, serving as a culture substrate, to promote adult NP cells to undergo a shift from a degenerative fibroblast-like state to a juvenile-like NP phenotype. In the current study, we evaluate the ability for this peptide-functionalized hydrogel to serve as a bioactive system for cell delivery, retention and preservation of a biosynthetic phenotype for primary IVD cells delivered to the rat caudal disc in an anular puncture degeneration model. Our data suggest that encapsulation of adult degenerative human NP cells in a stiff formulation of the hydrogel functionalized with laminin-mimetic peptides IKVAV and AG73 can promote cell viability and increased biosynthetic activity for this population in 3D culture in vitro. Delivery of the peptide-functionalized biomaterial with primary rat cells to the degenerated IVD supported NP cell retention and NP-specific protein expression in vivo, and promoted improved disc height index (DHI) values and endplate organization compared to untreated degenerated controls. The results of this study suggest the physical cues of this peptide-functionalized hydrogel can serve as a supportive carrier for cell delivery to the IVD. Statement of significanceCell delivery into the degenerative intervertebral disc has been widely explored as a strategy to supplement the nucleus pulposus. The current work seeks to employ a biomaterial functionalized with laminin-mimetic peptides as a cell delivery scaffold in order to improve cell retention rates within the intradiscal space, while providing the delivered cells with biomimetic cues in order to promote phenotypic expression and increase biosynthetic activity. The use of the in situ crosslinkable material integrated with the native IVD, presenting a system with adequate physical properties to support a degenerative disc.

PLGA hybrid porous microspheres as human periodontal ligament stem cell delivery carriers for periodontal regeneration

Periodontitis, a widespread disease, is the main cause of tooth loss in adults, and there is no ideal clinical therapy for patients with severe alveolar bone defects. Research investigating the potential of polymer porous microspheres (PMs) as stem cells delivery carriers has been a hot-spot topic for tissue engineering in recent years. However, to date, it remains largely unknown regarding application of PMs in periodontal regeneration with satisfied cell seeding efficiency. In this study, PLGA PMs and corresponding silk fibroin (SF) or / and hydroxyapatite (HA) modified PLGA counterparts were synthesized by double emulsion-solvent evaporation, desolvation and biomineralization. Then, human periodontal ligament stem cells (hPDLSCs) were seeded into these carriers with a specific “cell perfusion” technique. Cell viability and migration, proliferation as well as osteogenic differentiation properties of the hPDLSCs were evaluated in vitro. In vivo experiment examining the impact of hPDLSCs suspension group and four cell delivery carriers groups on rat periodontal tissue regeneration further suggested that the HA-SF-PLGA group displayed superior tissue repairing efficacy due to SF-dependent high adhesion and HA-dependent osteogenesis induction. This novel tissue regeneration strategy based on PLGA hybrid PMs combined with a specific “cell perfusion” technique present promising potential of local stem cell delivery for effective clinical periodontitis therapy development, which is also applicable to tissue regeneration in other body parts.

Injectable GelMA Cryogel Microspheres for Modularized Cell Delivery and Potential Vascularized Bone Regeneration.

Cell therapeutics hold tremendous regenerative potential and the therapeutic effect depends on the effective delivery of cells. However, current cell delivery carriers with unsuitable cytocompatibility and topological structure demonstrate poor cell viability during injection. Therefore, porous shape-memory cryogel microspheres (CMS) are prepared from methacrylated gelatin (GelMA) by combining an emulsion technique with gradient-cooling cryogelation. Pore sizes of the CMS are adjusted via the gradient-cooling procedure, with the optimized pore size (15.5± 6.0µm) being achieved on the 30-min gradient-cooled variant (CMS-30). Unlike hydrogel microspheres (HMS), CMS promotes human bone marrow stromal cell (hBMSC) and human umbilical vein endothelial cell (HUVEC) adhesion, proliferated with high levels of stemness for 7 d, and protects cells during the injection process using a 26G syringe needle. Moreover, CMS-30 enhances the osteogenic differentiation of hBMSCs in osteoinductive media. CMS can serve as building blocks for delivering multiple cell types. Here, hBMSC-loaded and HUVEC-loaded CMS-30, mixed at a 1:1 ratio, are injected subcutaneously into nude mice for 2 months. Results show the development of vascularized bone-like tissue with high levels of OCN and CD31. These findings indicate that GelMA CMS of a certain pore size can effectively deliver multiple cells to achieve functional tissue regeneration.

Evaluation of bone regeneration in mandible large defect using undifferentiated adipose stem cells loaded on gelatin carrier: An animal model case study

Background. Large mandibular defects are considered difficult reconstructive challenges for oral and maxillofacial surgeons. Cell therapy, as an alternative technique, might increase the speed of bone regeneration. This study aimed to investigate bone regeneration in large defects of dog mandibles using allogenic adipose-derived stem cells on gelatin foam as a cell carrier. Methods. The tissue engineering phase consisted of the sampling of adult dogs’ adipose tissue that can easily be isolated from adipose stem cells (ASCs) of the dogs, ASCs were cultured in Dulbecco’s Modified Eagle’s Medium (DMEM, Gibco, USA) with low glucose, containing 10% fetal bovine serum (FBS) (Sigma, USA) and 1% penicillin-streptomycin (Gibco, USA), with the characterization of dog ASCs and gelatin-transplanted ASCs. Six dogs were included in this experimental study in the next step and randomly assigned to the treatment and control groups. The samples in both groups underwent surgery under general anesthesia to create uniform 3-cm bony defects. The samples in both groups were reconstructed with titanium reconstruction plates and screws. A large bone gap filled with ASCs (5×106 ) was seeded on gelatin (ASCs) in the treatment group. In the control group, bony defects were filled with a cell delivery carrier without ASCs. Six months after transplantation, the animals’ mandibles were evaluated by CT scan imaging, and the results were quantified through the Hounsfield unit (HU). The data were analyzed with t-test. Results. Before transplantation, the nature of the stem cells was confirmed by the expression of CD44 and CD105 cell markers at 71.9% and 89.3%, respectively, and a lack of the CD45 cell marker expression at 2.2%. Evaluation of CT scan images showed significantly higher bone repair in the ASCs group (920.25±572.92 HU) than in the control group (-94.746± 08.42). Conclusion. The bone regeneration of the ASCs group was significantly higher than that in the control group.

Intraocular Injection of HyStem Hydrogel Is Tolerated Well in the Rabbit Eye.

Purpose: To determine the long-term biocompatibility of HyStem® hydrogel in the rabbit eye for use as a carrier for cell or drug delivery into the ocular space. Methods: HyStem hydrogel formulation solidifies ∼20 min after reconstitution, thus can potentially form a solid deposit after injection in situ. To study the ocular disposition of fluorescein-labeled HyStem, we delivered 50 μL/eye over 1 min into the vitreous space of the rabbit. We used 3 Dutch-Belted and 3 New Zealand-pigmented rabbits, all females, delivered the gel into the right eyes, and injected 50 μL BSS Plus into the left eyes as a control. Retinal morphology was assessed by optical coherence tomography (OCT) and white light fundus photography. Fluorescence fundus photography enabled measurement of the clearance of the labeled hydrogel from the posterior chamber. Visual function was evaluated using flash and flicker electroretinography (ERG) pre- and postinjection and at weekly intervals thereafter for 6 weeks. Retinal immunohistochemistry for microglial inflammatory markers was carried out with antiglial fibrillary acidic protein (GFAP) antibody, isolectin B4 (IB4), and 4',6-diamidino-2-phenylindole (DAPI). Results: The gel was successfully delivered into the vitreous space without the formation of a discrete retinal deposit. Fundus imaging, OCT measurements of retinal thickness, and immunohistochemical data indicated an absence of retinal inflammation, and ERG indicated no impact on retinal function. The half-time of HyStem clearance calculated from the loss of fundus fluorescence was 3.9 days. Conclusions: HyStem hydrogel appears to be biocompatible in the ocular space of a large eye and safe for long-term intraocular application.

Injectable Hydrogel ­Mediated Delivery of Gene-Engineered Adipose-Derived Stem Cells for Enhanced Osteoarthritis Treatment

Osteoarthritis (OA), a chronic and degenerative joint disease, remains a challenge in treatment due to the lack of disease-modifying therapies. As a promising therapeutic agent, adipose-derived stem cells (ADSCs) perform an effective anti-inflammatory and chondroprotective paracrine effect that could be enhanced by genetic modification. Unfortunately, direct cell delivery without matrix support often results in poor viability of therapeutic cells. Herein, a hydrogel implant approach that enabled intra-articular delivery of gene-engineered ADSCs was developed for improved therapeutic outcomes in a surgically induced rat OA model. An injectable extracellular matrix (ECM)-mimicking hydrogel was prepared as the carrier for cell delivery, providing a favorable micro-environment for ADSCs spreading and proliferation. The ECM-mimicking hydrogel could reduce cell death during and post-injection. Additionally, ADSCs were genetically modified to overexpress transforming growth factor-β1 (TGF-β1), one of the paracrine factors that exert an anti-inflammatory and pro-anabolic effect. The gene-engineered ADSCs overexpressing TGF-β1 (T-ADSCs) perform an enhanced paracrine effect on OA-like chondrocytes, which effectively decreases the expression of tumor necrosis factor-alpha ( TNF-α ) and increases the expression of collagen II and aggrecan. In the surgically induced rat OA model, intra-articular injection of T-ADSCs-loaded hydrogel remarkedly reduced the cartilage degeneration, joint inflammation, and loss of subchondral bone. Taken together, this study provides a potential biomaterial strategy for enhanced OA treatment by delivering the gene-engineered ADSCs within an ECM-mimicking hydrogel.