Adipose-Derived Stem Cells (ADSCs) Loaded Gelatin-Sericin-Laminin Cryogels for Tissue Regeneration in Diabetic Wounds.

Healing in wounds like pressure ulcers, diabetic ulcers, venous ulcers, and arterial insufficiency ulcers is immensely hampered and causes both an economic burden and morbidity to patients. These wounds face a plethora of hostile conditions like elevated reactive oxygen species (ROS), impaired angiogenesis, senescent fibroblasts, and deficient stem cells that significantly diminish the probability of self-healing in these wounds. Adipose-derived stem cell therapy (ADSC) presents a promising approach to achieve efficient healing in such cases. To address the complex scenario of chronic wounds, we propose a combinatorial approach of delivering ADSCs on antioxidant gelatin-sericin (GS) scaffolds coated with laminin (GSL), an endothelial basement protein to improve angiogenesis. The synthesized GS scaffolds showed values of compression modulus, pore size, porosity, and the swelling ratio in the range of 65 kPa, 158 ± 48.8 µm, 91.1% ± 1.25, and 28 ± 2.5, respectively. A DPPH assay revealed GS scaffolds exhibit around 20% more scavenging as against gelatin (G) scaffolds and better protection against free radical assault, thus enhancing cell viability and the metabolic index of fibroblast cells. Different cells, namely, fibroblasts, keratinocytes, and ADSCs, cultured on GS scaffolds had better metabolic activity as compared with G scaffolds. Laminin coating onto the scaffolds leads to improved attachment and tube formation of endothelial cells as depicted in scanning electron microscopy images. Finally, we validated the applicability of the ADSCs loaded laminin-coated GS scaffolds in a diabetic ulcer rat model. Hematoxylin and eosin, Masson's trichrome, and picrosirius red staining showed better regeneration and collagen remodeling in ADSCs loaded GSL scaffolds. Immunostaining of CD31 staining demonstrates enhanced angiogenesis in GSL-ADSC as compared with other groups.

Aligned Chitosan-Gelatin Cryogel-Filled Polyurethane Nerve Guidance Channel for Neural Tissue Engineering: Fabrication, Characterization, and In Vitro Evaluation.

Recent trends in peripheral nerve regeneration are directed toward the development of nerve guidance channels to assist the regeneration of the nerves across critical size defects. Advanced nerve guidance channels (aNGCs) should possess multifunctional properties to direct the axonal regeneration from proximal to distal end, allow the concentration of growth factors secreted by the injured nerve end, and attenuate the ingrowth of scar tissue at the site of injury. The design of the nerve guidance channel (NGC) is critical for providing the necessary topographical, chemotactic, as well as haptotactic cues for efficient nerve regeneration. In this study, we have designed and fabricated clinically relevant aNGCs comprising an antioxidant polyurethane (PUAO) conduit filled with aligned chitosan-gelatin (CG) cryogel filler for peripheral nerve regeneration. The effects of temperature, polymer concentration, and cross-linker concentration on the physicochemical properties of the CG cryogel filler were studied. The synthesized scaffolds were evaluated by scanning electron microscopy (SEM) and compression testing to obtain the matrix best suited to form the aNGC. The nanofibrous PUAO conduit was fabricated by electrospinning with a wall thickness of 114.16 ± 26.91 µm, which was filled with CG (1.2/6.4%)-aligned cryogel matrix to obtain the aNGCs. The aNGCs with 2.01 ± 0.04 mm internal diameter, 15 mm length, and internal CG filler with a pore diameter of 29.60 ± 9.83 µm were fabricated. The aNGCs were evaluated by SEM and in vitro neuronal culture for biocompatibility and cellular alignment. In vitro dorsal root ganglion cultures showed the aligned growth and cellular migration along the aligned pores of aNGCs. With this study, we conclude that this clinically relevant aligned porous aNGC will have a promising effect in repair and regeneration of peripheral nerve injuries.

Exosomes in nanomedicine: a promising cell-free therapeutic intervention in burn wounds.

Burn injuries are serious injuries that have a big impact on a person's health and can even cause death. Incurring severe burns can incite an immune response and inflammation within the body, alongside metabolic changes. It is of utmost importance to grasp the fact that the effects of the burn injury extend beyond the body, affecting the mind and overall well-being. Burn injuries cause long-lasting changes that need to be taken care of in order to improve their quality of life. The intricate process of skin regeneration at the site of a burn wound involves a complex and dynamic interplay among diverse cells, growth factors, nerves, and blood vessels. Exciting opportunities have arisen in the field of stem cells and regenerative medicine, allowing us to explore the development of cell-free-based alternatives that can aid in the treatment of burn injuries. These cell-free-based therapies have emerged as a promising facet within regenerative medicine. Exosomes, also referred to as naturally occurring nanoparticles, are small endosome-derived vesicles that facilitate the delivery of molecular cargo between the cells, thus allowing intercellular communication. The knowledge gained in this field has continued to support their therapeutic potential, particularly in the domains of wound healing and tissue regeneration. Notably, exosomes derived from mesenchymal stem cells (MSCs) can be safely administered in the system, which is then adeptly uptaken and internalized by fibroblasts/epithelial cells, subsequently accelerating essential processes such as migration, proliferation, and collagen synthesis. Furthermore, exosomes released by immune cells, specifically macrophages, possess the capability to modulate inflammation and effectively diminish it in adjacent cells. Exosomes also act as carriers when integrated with a scaffold, leading to scarless healing of cutaneous wounds. This comprehensive review examines the role of exosomes in burn wound healing and their potential utility in regeneration and repair.

Extracellular vesicles derived from mesenchymal stem cells - a novel therapeutic tool in infectious diseases.

Extracellular vesicles (EVs) are nano-sized lipid-bilayer encapsulated vesicles produced by the cells. These EVs are released into the surrounding space by almost all cell types. The EVs help in intercellular communication via their payloads which contain various proteins, lipids, and nucleic acids generated from the donor cells and allow for synergistic responses in surrounding cells. In recent years, EVs have been increasingly important in treating infectious diseases, including respiratory tract infections, urinary tract infections, wound infections, sepsis, and intestinal infections. Studies have confirmed the therapeutic value of mesenchymal stem cell-derived EVs (MSC-EVs) for treating infectious diseases to eliminate the pathogen, modulate the resistance, and restore tissue damage in infectious diseases. This can be achieved by producing antimicrobial substances, inhibiting pathogen multiplication, and activating macrophage phagocytic activity. Pathogen compounds can be diffused by inserting them into EVs produced and secreted by host cells or by secreting them as microbial cells producing EVs carrying signalling molecules and DNA shielding infected pathogens from immune attack. EVs play a key role in infectious pathogenesis and hold great promise for developing innovative treatments. In this review, we discuss the role of MSC-EVs in treating various infectious diseases.

Data supporting exosome laden oxygen releasing antioxidant and antibacterial cryogel wound dressing OxOBand alleviate diabetic and infectious wound healing.

Hypoxia, reduced vascularization, elevated oxidative stress, and infection are critical clinical hallmarks of non-healing chronic diabetic wounds. The dataset presented here is in support of the development and evaluation of the exosome laden oxygen releasing OxOBand for treatment and management of diabetic and infectious wounds [1]. It describes the additional results in support of the development of OxOBand and its evaluation for diabetic wound healing. Exosomes were isolated from adipose-derived stem cells (ADSCs) and characterized through dynamic light scattering (DLS) and scanning electron microscopy (SEM). The encapsulation of exosomes by cells and its effect on migration of NIH3T3 cells under in-vitro condition is described. Further antioxidant polyurethane (PUAO) cryogel and oxygen releasing antioxidant (PUAO-CPO) cryogel scaffolds were fabricated as reported earlier [2,3] and NIH3T3, HaCaT and ADSCs were cultured on these scaffolds. "OxOBand", the calcium peroxide containing oxygen releasing antioxidant polyurethane (PUAO-CPO) scaffold along with exosomes was evaluated in chronic wounds in diabetic rats. The wounds were also infected with Staphylococcus aureus (S. aureus), and Pseudomonas aeruginosa (P. aeruginosa) bacteria and OxOBand was further evaluated for the healing of these infectious diabetic wounds. Interpretation of this data can be found in a research article title "Exosome laden oxygen releasing antioxidant and antibacterial cryogel wound dressing OxOBand alleviate diabetic and infectious wound healing, Shiekh et. al., Biomaterials, 2020 [1].

Exosome laden oxygen releasing antioxidant and antibacterial cryogel wound dressing OxOBand alleviate diabetic and infectious wound healing.

Lack of oxygen, reduced vascularization, elevated oxidative stress, and infection are critical clinical hallmarks of non-healing chronic diabetic wounds. Therefore, delivering oxygen, inducing angiogenesis, and management of oxidative stress and infection may provide newer and improved therapeutic avenues for better clinical outcomes in diabetic wound healing. Here, we report the development and evaluation of an exosome laden oxygen releasing antioxidant wound dressing OxOBand to promote wound closure and skin regeneration in diabetic wounds. OxOBand is composed of antioxidant polyurethane (PUAO), as highly porous cryogels with sustained oxygen releasing properties and supplemented with adipose-derived stem cells (ADSCs) exosomes. Exosomes engulfed by the cells enhanced the migration of human keratinocytes and fibroblasts and increased the survival of human neuroblastoma cells under hyperglycemic conditions. OxOBand facilitated faster wound closure, enhanced collagen deposition, faster re-epithelialization, increased neo-vascularization, and decreased oxidative stress within two weeks as compared to untreated diabetic control wounds. The dressing promoted the development of mature epithelial structures with hair follicles and epidermal morphology similar to that of healthy skin. In clinically challenging infected diabetic wounds, these dressings prevented infection and ulceration, improved wound healing with increased collagen deposition, and re-epithelialization. Altogether, OxOBand is a remarkably newer treatment strategy for enhanced diabetic wound healing and may lead to novel therapeutic interventions for the treatment of diabetic ulcers.

Engineering Bioinspired Antioxidant Materials Promoting Cardiomyocyte Functionality and Maturation for Tissue Engineering Application.

Oxidative stress plays an important role in various pathological conditions, such as wound healing, inflammation, myocardial infarction, and biocompatibility of the materials. Antioxidant polymers to attenuate oxidative stress is an emerging field of biomaterial research with a huge impact in the field of tissue engineering and regenerative medicine. We describe here the fabrication and evaluation of an elastomeric antioxidant polyurethane (PUAO) for tissue engineering applications. Uniaxial and cyclic tensile testing, thermal analysis, degradation, cytotoxicity and antioxidant analysis was carried out. An in vitro oxidative stress model demonstrated that PUAO reduced intracellular oxidative stress in H9C2 cardiomyocytes (p < 0.05) and attenuated reactive oxygen species (ROS) induced cell death (p < 0.001). Under simulated ischemic reperfusion, PUAO could rescue hypoxia induced cell death. Further as a proof of concept, neonatal rat cardiomyocytes cultured on PUAO film displayed synchronous beating with mature phenotype showing expression of cardiac specific α-actinin, troponin-T, and connexin-43 proteins. Intracellular calcium transients established the functionality of cultured cardiomyocytes on PUAO film. Our study demonstrated the potential of this biomaterial to be developed into tissue engineered scaffold to attenuate oxidative stress for treatment of diseased conditions with increased oxidative stress, such as cardiovascular diseases, chronic wound healing, and myocardial infarction.

Oxygen-Releasing Antioxidant Cryogel Scaffolds with Sustained Oxygen Delivery for Tissue Engineering Applications.

With the advancement in biomaterial sciences, tissue-engineered scaffolds are developing as a promising strategy for the regeneration of damaged tissues. However, only a few of these scaffolds have been translated into clinical applications. One of the primary drawbacks of the existing scaffolds is the lack of adequate oxygen supply within the scaffolds. Oxygen-producing biomaterials have been developed as an alternate strategy but are faced with two major concerns. One is the control of the rate of oxygen generation, and the other is the production of reactive oxygen species (ROS). To address these concerns, here, we report the development of an oxygen-releasing antioxidant polymeric cryogel scaffold (PUAO-CPO) for sustained oxygen delivery. PUAO-CPO scaffold was fabricated using the cryogelation technique by the incorporation of calcium peroxide (CPO) in the antioxidant polyurethane (PUAO) scaffolds. The PUAO-CPO cryogels attenuated the ROS and showed a sustained release of oxygen over a period of 10 days. An in vitro analysis of the PUAO-CPO cryogels showed their ability to sustain H9C2 cardiomyoblast cells under hypoxic conditions, with cell viability being significantly better than the normal polyurethane (PU) scaffolds. Furthermore, in vivo studies using an ischemic flap model showed the ability of the oxygen-releasing cryogel scaffolds to prevent tissue necrosis upto 9 days. Histological examination indicated the maintenance of tissue architecture and collagen content, whereas immunostaining for proliferating cell nuclear antigen confirmed the viability of the ischemic tissue with oxygen delivery. Our study demonstrated an advanced approach for the development of oxygen-releasing biomaterials with sustained oxygen delivery as well as attenuated production of residual ROS and free radicals because of ischemia or oxygen generation. Hence, the oxygen-releasing PUAO-CPO cryogel scaffolds may be used with cell-based therapeutic approaches for the regeneration of damaged tissue, particularly with ischemic conditions such as myocardial infarction and chronic wound healing.

Biomimetic Photocurable Three-Dimensional Printed Nerve Guidance Channels with Aligned Cryomatrix Lumen for Peripheral Nerve Regeneration.

Repair and regeneration of critically injured peripheral nerves is one of the most challenging reconstructive surgeries. Currently available and FDA approved nerve guidance channels (NGCs) are suitable for small gap injuries, and their biological performance is inferior to that of autografts. Development of biomimetic NGCs with clinically relevant geometrical and biological characteristics such as topographical, biochemical, and haptotactic cues could offer better regeneration of the long-gap complex nerve injuries. Here, in this study, we present the development and preclinical analysis of three-dimensional (3D) printed aligned cryomatrix-filled NGCs along with nerve growth factor (NGF) (aCG + NGF) for peripheral nerve regeneration. We demonstrated the application of these aCG + NGF NGCs in the enhanced and successful regeneration of a critically injured rat sciatic nerve in comparison to random cryogel-filled NGCs, multichannel and clinically preferred hollow conduits, and the gold standard autografts. Our results indicated similar effect of the aCG + NGF NGCs viz-a-viz that of the autografts, and they not only enhanced the overall regenerated nerve physiology but could also mimic the cellular aspects of regeneration. This study emphasizes the paradigm that these biomimetic 3D printed NGCs will lead to a better functional regenerative outcome under clinical settings.