Exosome-loaded decellularized tissue: Opening a new window for regenerative medicine.

Mesenchymal stem cell-derived exosomes (MSCs-EXO) have received a lot of interest recently as a potential therapeutic tool in regenerative medicine. Extracellular vesicles (EVs) known as exosomes (EXOs) are crucial for cell-cell communication throughout a variety of activities including stress response, aging, angiogenesis, and cell differentiation. Exploration of the potential use of EXOs as essential therapeutic effectors of MSCs to encourage tissue regeneration was motivated by success in the field of regenerative medicine. EXOs have been administered to target tissues using a variety of methods, including direct, intravenous, intraperitoneal injection, oral delivery, and hydrogel-based encapsulation, in various disease models. Despite the significant advances in EXO therapy, various methods are still being researched to optimize the therapeutic applications of these nanoparticles, and it is not completely clear which approach to EXO administration will have the greatest effects. Here, we will review emerging developments in the applications of EXOs loaded into decellularized tissues as therapeutic agents for use in regenerative medicine in various tissues.

The wound healing effect of polycaprolactone-chitosan scaffold coated with a gel containing Zataria multiflora Boiss. volatile oil nanoemulsions.

AIMS: Thymus plant is a very useful herbal medicine with various properties such as anti-inflammatory and antibacterial. Therefore, the properties of this plant have made this drug a suitable candidate for wound healing. In this study, hydroxypropyl methylcellulose (HPMC) gel containing Zataria multiflora volatile oil nanoemulsion (neZM) along with polycaprolactone/chitosan (PCL-CS) nanofibrous scaffold was used, and the effect of three experimental groups on the wound healing process was evaluated. The first group, HPMC gel containing neZM, the second group, PCL-CS nanofibers, and the third group, HPMC gel containing neZM and bandaged with PCL-CS nanofibers (PCL-CS/neZM). Wounds bandaged with common sterile gas were considered as control. METHODS: The nanoemulsion was synthesized by a spontaneous method and loaded into a hydroxypropyl methylcellulose (HPMC) gel. The DLS test investigated the size of these nanoemulsions. A PCL-CS nanofibrous scaffold was also synthesized by electrospinning method then SEM and contact angle tests investigated morphology and hydrophilicity/hydrophobicity of its surface. The animal study was performed on full-thickness skin wounds in rats, and the process of tissue regeneration in the experimental and control groups was evaluated by H&E and Masson's trichrome staining. RESULTS: The results showed that the nanoemulsion has a size of 225±9 nm and has an acceptable dispersion. The PCL-CS nanofibers synthesized by the electrospinning method also show non-beaded smooth fibers and due to the presence of chitosan with hydrophilic properties, have higher surface hydrophobicity than PCL fibers. The wound healing results show that the PCL-CS/neZM group significantly reduced the wound size compared to the other groups on the 7th, 14th, and 21st days. The histological results also show that the PCL-CS/neZM group could significantly reduce the parameters of edema, inflammation, and vascularity and increase the parameters of fibrosis, re-epithelialization, and collagen deposition compared to other groups on day 21. CONCLUSION: The results of this study show that the PCL-CS/neZM treatment can effectively improve wound healing.

The novel treatments based on tissue engineering, cell therapy and nanotechnology for cutaneous leishmaniasis.

Cutaneous leishmaniasis (CL) is a global public health issue. Conventional treatments have substantial costs, side effects, and parasite resistance. Due to easy application and inexpensive cost, topical treatment is the optimal approach for CL. It could be used alone or with systemic treatments. Electrospun fibers as drug release systems in treating skin lesions have various advantages such as adjustable drug release rate, maintaining appropriate humidity and temperature, gas exchange, plasticity at the lesion site, similarity with the skin extracellular matrix (ECM) and drug delivery with high efficiency. Hydrogels are valuable scaffolds in the treatment of skin lesions. The important features of hydrogels include preserving unstable drugs from degradation, absorption of wound secretions, high biocompatibility, improving the re-epithelialization of the wound and preventing the formation of scars. One of the issues in local drug delivery systems for the skin is the low permeability of drugs in the skin. Polymeric scaffolds that are designed as microneedle patches can penetrate the skin and overcome this challenge. Also, drug delivery using nanocarriers increases the effectiveness of drugs in lower and more tolerable doses and reduces the toxicity of drugs. The application of cell therapy in the treatment of parasitic and infectious diseases has been widely investigated. The complexity of leishmaniasis treatment requires identifying new treatment options like cell therapy to overcome the disease. Topics investigated in this study include drug delivery systems based on tissue engineering scaffolds, nanotechnology and cell therapy-based studies to reduce the complications of CL.

Nerve regeneration using decellularized tissues: challenges and opportunities.

In tissue engineering, the decellularization of organs and tissues as a biological scaffold plays a critical role in the repair of neurodegenerative diseases. Various protocols for cell removal can distinguish the effects of treatment ability, tissue structure, and extracellular matrix (ECM) ability. Despite considerable progress in nerve regeneration and functional recovery, the slow regeneration and recovery potential of the central nervous system (CNS) remains a challenge. The success of neural tissue engineering is primarily influenced by composition, microstructure, and mechanical properties. The primary objective of restorative techniques is to guide existing axons properly toward the distal end of the damaged nerve and the target organs. However, due to the limitations of nerve autografts, researchers are seeking alternative methods with high therapeutic efficiency and without the limitations of autograft transplantation. Decellularization scaffolds, due to their lack of immunogenicity and the preservation of essential factors in the ECM and high angiogenic ability, provide a suitable three-dimensional (3D) substrate for the adhesion and growth of axons being repaired toward the target organs. This study focuses on mentioning the types of scaffolds used in nerve regeneration, and the methods of tissue decellularization, and specifically explores the use of decellularized nerve tissues (DNT) for nerve transplantation.

Advantages of Material Biofunctionalization Using Nucleic Acid Aptamers in Tissue Engineering and Regenerative Medicine.

Material engineering is a fundamental issue in the applications of materials in the medical field. One of the aspects of material engineering is incorporating recognition sites on the surface of biomaterials, which plays an essential role in increasing the efficiency of tissue engineering scaffolds in various aspects. The application of peptides and antibodies to establish the recognition and adhesion sites has limitations, such as fragility and instability under physical and chemical processes. Therefore, synthetic ligands such as nucleic acid aptamers have received much attention for easy synthesis, minimal immunogenicity, high specificity, and stability under processing. Due to the effective role of these ligands in increasing the efficiency of engineered constructs in this study, the advantages of nucleic acid aptamers in tissue engineering will be reviewed. Aptamer-functionalized biomaterials can attract endogenous stem cells to wounded areas and organize their actions to facilitate tissue regeneration. This approach harnesses the body's inherent regeneration potential to treat many diseases. Also, increased efficacy in controlled release, slow and targeted drug delivery are important issues in drug delivery for tissue engineering approaches which can be achieved by incorporating aptamers in drug delivery systems. Aptamer-functionalized scaffolds have very applications, such as diagnosis of cancer, hematological infections, narcotics, heavy metals, toxins, controlled release from the scaffolds, and in vivo cell tracing. Aptasensors, as a result of many advantages over other traditional assay methods, can replace older methods. Furthermore, their unique targeting mechanism also targets compounds with no particular receptors. Targeting cell homing, local and targeted drug delivery, cell adhesion efficacy, cytocompatibility and bioactivity of scaffolds, aptamer-based biosensor, and aptamer-functionalized scaffolds are the topics that will be examined in this review study.

Liposomal nanocarriers containing siRNA as small molecule-based drugs to overcome cancer drug resistance.

This review discusses the application of nanoliposomes containing siRNA/drug to overcome multidrug resistance for all types of cancer treatments. As drug resistance-associated factors are overexpressed in many cancer cell types, pumping chemotherapy drugs out of the cytoplasm leads to an inadequate therapeutic response. The siRNA/drug-loaded nanoliposomes are a promising approach to treating multidrug-resistant cancer, as they can effectively transmit a small-molecule drug into the target cytoplasm, ensuring that the drug binds efficiently. Moreover, nanoliposome-based therapeutics with advances in nanotechnology can effectively deliver siRNA to cancer cells. Overall, nanoliposomes have the potential to effectively deliver siRNA and small-molecule drugs in a targeted manner and are thus a promising tool for the treatment of cancer and other diseases.

Development of meniscus cartilage using polycaprolactone and decellularized meniscus surface modified by gelatin, hyaluronic acid biomacromolecules: A rabbit model.

The lack of vascularization in the white-red and white zone of the meniscus causes these zones of tissue to have low self-healing capacity in case of injury and accelerate osteoarthritis (OA). In this study, we have developed hybrid constructs using polycaprolactone (PCL) and decellularized meniscus extracellular matrix (DMECM) surface modified by gelatin (G), hyaluronic acid (HU) and selenium (Se) nanoparticles (PCL/DMECM/G/HU/Se), following by the cross-linking of the bio-polymeric surface. Material characterization has been performed on the fabricated scaffold using scanning electron microscopy (SEM), Fourier transforms infrared (FTIR) spectroscopy, swelling and degradation analyses, and mechanical tests. In Vitro, investigations have been conducted by C28/I2 human chondrocyte culture into the scaffold and evaluated the cytotoxicity and cell/scaffold interaction. For the in vivo study, the scaffolds were transplanted into the defect sites of female New Zealand white rabbits. Good regeneration was observed after two months. We have concluded that the designed PCL/DMECM/G/HU construct can be a promising candidate as a meniscus tissue engineering scaffold to facilitate healing.

Engineered cells along with smart scaffolds: critical factors for improving tissue engineering approaches.

In this review, gene delivery and its applications are discussed in tissue engineering (TE); also, new techniques such as the CRISPR-Cas9 system, synthetics biology and molecular dynamics simulation to improve the efficiency of the scaffolds have been studied. CRISPR-Cas9 is expected to make significant advances in TE in the future. The fundamentals of synthetic biology have developed powerful and flexible methods for programming cells via artificial genetic circuits. The combination of regenerative medicine and artificial biology allows the engineering of cells and organisms for use in TE, biomaterials, bioprocessing and scaffold development. The dynamics of protein adsorption at the scaffold surface at the atomic level can provide valuable guidelines for the future design of TE scaffolds /implants.

Characterization of Macroporous Polycaprolactone/Silk Fibroin/Gelatin/Ascorbic Acid Composite Scaffolds and In Vivo Results in a Rabbit Model for Meniscus Cartilage Repair.

OBJECTIVE: Meniscus injuries in the inner avascular zone have weak intrinsic self-healing capacity and often progress to osteoarthritis. This study focused on evaluating the effects of polycaprolactone/silk fibroin/gelatin/ascorbic acid (PCL/SF/Gel/AA) composite scaffolds seeded with adipose-derived mesenchymal stem cells (ASCs), in the meniscus repair. DESIGN: To this end, composite scaffolds were cross-linked using N-hydroxysuccinimide and 1-ethyl-3-(3-dimethyl-aminopropyl)-1-carbodiimide hydrochloride. Scaffolds were then characterized by scanning electron microscope, mechanical tests, total antioxidant capacity, swelling, and toxicity tests. RESULTS: The PCL/SF/Gel/AA scaffolds exhibited suitable mechanical properties. Furthermore, vitamin C rendered them the highest antioxidant capacity. The PCL/SF/Gel/AA scaffolds also showed good biocompatibility and proliferation for chondrocytes. Moreover, the PCL/SF/Gel/AA scaffold seeded with allogeneic ASCs was engrafted in New Zealand rabbits who underwent unilateral punch defect in the medial meniscus of the right knee. After 2 months postimplantation, macroscopic and histologic studies for new meniscus cartilage were performed. CONCLUSIONS: Our results indicated that the PCL/SF/Gel/AA composite scaffolds seeded with allogeneic ASCs could successfully improve meniscus healing in damaged rabbits.

Macroporous scaffold surface modified with biological macromolecules and piroxicam-loaded gelatin nanofibers toward meniscus cartilage repair.

Meniscus cartilage has poor self-healing capacity in the inner zone and its damage leads to articular cartilage degeneration. Here we have developed hybrid constructs using polycaprolactone (PCL) and polyurethane (PU) surface modified by gelatin (G), chitosan (C), and hyaluronic acid (H) biomacromolecules and piroxicam-loaded gelatin nanofibers (PCL/PU/GCH/P). The surface of constructs was crosslinked using EDC and NHS. The scaffolds were investigated by SEM, FTIR spectroscopy, swelling test, degradation rate, mechanical tests, and in vitro piroxicam release assay. Furthermore, the cell-seeded scaffolds were evaluated by SEM, viability assay, dapi staining, cell migration, proliferation, and gene expression of chondrocytes within these scaffolds. Finally, the animal study was performed in a rabbit model. Chondrocyte and rabbit adipose-derived mesenchymal stem cells (ASCs) from the infrapatellar fat pad (Hoffa's fat pad) were used. Swelling and degradation rate were increased in the modified scaffolds. Tensile and compressive Young's modulus also were near to human native meniscus tissue. The highest expression level of chondrocyte marker genes was observed for the PCL/PU/GCH scaffold. A significant regeneration was obtained in rabbits treated with ASCs-loaded PCL/PU/GCH/P scaffold after 3 months. The surface-modified scaffolds with or without ASCs could successfully accelerate meniscus regeneration and exhibit potential application in meniscus tissue engineering.

Corneal epithelium tissue engineering: recent advances in regeneration and replacement of corneal surface.

Currently, many corneal diseases are treated by corneal transplantation, artificial corneal implantation or, in severe cases, keratoprosthesis. Owing to the shortage of cornea donors and the risks involved with artificial corneal implants, such as infection transmission, researchers continually seek new approaches for corneal regeneration. Corneal tissue engineering is a promising approach that has attracted much attention from researchers and is focused on regenerative strategies using various biomaterials in combination with different cell types. These constructs should have the ability to mimic the native tissue microenvironment and present suitable optical, mechanical and biological properties. In this article, we review studies that have focused on the current clinical techniques for corneal replacement. We also describe tissue-engineering and cell-based approaches for corneal regeneration.

Chondrocytes Proliferation of Patients with Cartilage Lesions in Their Own Body for Use in Cartilage Tissue Engineering: Hypotheses on a New Approach for the Proliferation of Autologous Chondrocytes.

Osteoarthritis is one of the most common chronic diseases, which have involved 250 million people around the world. One of the challenges in the field of cartilage tissue engineering is to provide an adequate source of chondrocytes to prevent changes in gene expression profile as a result of multiple passages.We hypothesized that by creating a low invasive lesion by scalpel or shear laser in the outer ear cartilage and stimulation of wound healing process, hyperplasia occurs and will provide an appropriate number of autologous chondrocytes for extraction and use in articular cartilage tissue engineering. Also, due to the effect of platelet-rich plasma and biomechanical forces in stimulating and accelerating of the repair process, these two factors can be used to achieve more desirable results.We describe a new approach to proliferate chondrocytes in the body. To evaluate this idea, various techniques of gene expression at the level of RNA or protein and animal experiments for histological studies can be used. Also, flowcytometry technique can be used to determine the cell viability and counting them.The use of autologous cell sources with minimal changes in gene expression profile can be promising in tissue engineering products.