Safety of grafting acellular human corneal lenticule seeded with Wharton's Jelly-Derived Mesenchymal Stem Cells in an experimental animal model

Application of mesenchymal stem cells derived from the umbilical cord or Wharton's jelly and their extracellular vesicles in the treatment of various diseases

Mesenchymal stem cells (MSCs) originating from the umbilical cord (UC) or Wharton's jelly (WJ) have attracted substantial interest due to their potential to augment therapeutic approaches for a wide range of disorders. These cells demonstrate a wide range of capabilities in the process of differentiating into a multitude of cell types. Additionally, they possess a significant capacity for proliferation and are conveniently accessible. Furthermore, they possess a status of being immune-privileged, exhibit minimal tumorigenic characteristics, and raise minimal ethical concerns. Consequently, they are well-suited candidates for tissue regeneration and the treatment of diseases. Additionally, UC-derived MSCs offer a substantial yield compared to other sources. The therapeutic effects of these MSCs are closely associated with the release of nanosized extracellular vesicles (EVs), including exosomes and microvesicles (MVs), containing lipids, microRNAs, and proteins that facilitate intercellular communication. Due to their reduced tumorigenic and immunogenic characteristics, in addition to their convenient manipulability, EVs have arisen as a viable alternative for the management of disorders. The favorable characteristics of UC-MSCs or WJ-MSCs and their EVs have generated significant attention in clinical investigations encompassing diverse pathologies. Therefore, we present a review encompassing current preclinical and clinical investigations, examining the implications of UC-MSCs in diverse diseases, including those affecting bone, cartilage, skin, liver, kidney, neural, lung, cardiovascular, muscle, and retinal tissues, as well as conditions like cancer, diabetes, sepsis, and others.

An inspired microenvironment of cell replicas to induce stem cells into keratocyte-like dendritic cells for corneal regeneration

Corneal stromal disorders due to the loss of keratocytes can affect visual impairment and blindness. Corneal cell therapy is a promising therapeutic strategy for healing corneal tissue or even enhancing corneal function upon advanced disorders, however, the sources of corneal keratocytes are limited for clinical applications. Here, the capacity of cell-imprinted substrates fabricated by molding human keratocyte templates to induce differentiation of human adipose-derived stem cells (hADSCs) into keratocytes, is presented. Keratocytes are isolated from human corneal stroma and grown to transmit their ECM architecture and cell-like topographies to a PDMS substrate. The hADSCs are then seeded on cell-imprinted substrates and their differentiation to keratocytes in DMEM/F12 (with and without chemical factors) are evaluated by real-time PCR and immunocytochemistry. The mesenchymal stem cells grown on patterned substrates present gene and protein expression profiles similar to corneal keratocytes. In contrast, a negligible expression of myofibroblast marker in the hADSCs cultivated on the imprinted substrates, is observed. Microscopic analysis reveals dendritic morphology and ellipsoid nuclei similar to primary keratocytes. Overall, it is demonstrated that biomimetic imprinted substrates would be a sufficient driver to solely direct the stem cell fate toward target cells which is a significant achievement toward corneal regeneration.

Combination of natural scaffolds and conditional medium to induce the differentiation of adipose-derived mesenchymal stem cells into keratocyte-like cells and its safety evaluation in the animal cornea

Keratocytes are the main cellular components of the corneal stroma. This cell is quiescent and cannot be cultured easily. The aim of this study was to investigate differentiate human adipose mesenchymal stem cells (hADSCs) into corneal keratocyte cells by combining natural scaffolds and conditioned medium (CM) and evaluating their safety in the rabbit's cornea. Keratocytes were cultured in an optimal culture medium and this medium was collected and kept as a CM. hADSCs were cultured on the decellularized human small incision lenticule extraction (SMILE) lenticule (SL), amniotic membrane (AM), and collagen-coated plates, and were exposed to keratocyte-CM (KCM) for 7, 14, and 21 days. Differentiation was evaluated using Real-time PCR and immunocytochemistry (ICC). hADSCs were cultured on the SL scaffolds and implanted in the corneal stroma of 8 New Zealand male rabbits. Rabbits were followed for 3 months and the safety was evaluated by clinical and histological variables. Real-time PCR results showed a significant increase in the expression of keratocyte-specific markers on the 21 day of differentiation compared to the control group. ICC also confirmed the induction of differentiation. Implantation of SLs containing differentiated cells in the cornea of animals showed no serious complications including neovascularization, corneal opacity, inflammation, or signs of tissue rejection. Furthermore, the evaluation of the presence of keratocyte-like cells after three months in the rabbit stroma was confirmed by Real-time PCR and immunohistochemistry (IHC) analysis. Our results showed that combination of combination of corneal extracellular matrix and KCM can induced keratocytes differentiation of hADSC and can be introduced as a alternative method to supply the required keratocytes in corneal tissue engineering.

Emerging tissue engineering strategies for the corneal regeneration

Cornea as the outermost layer of the eye is at risk of various genetic and environmental diseases that can damage the cornea and impair vision. Corneal transplantation is among the most applicable surgical procedures for repairing the defected tissue. However, the scarcity of healthy tissue donations as well as transplantation failure has remained as the biggest challenges in confront of corneal grafting. Therefore, alternative approaches based on stem-cell transplantation and classic regenerative medicine have been developed for corneal regeneration. In this review, the application and limitation of the recently-used advanced approaches for regeneration of cornea are discussed. Additionally, other emerging powerful techniques such as 5D printing as a new branch of scaffold-based technologies for construction of tissues other than the cornea are highlighted and suggested as alternatives for corneal reconstruction. The introduced novel techniques may have great potential for clinical applications in corneal repair including disease modeling, 3D pattern scheming, and personalized medicine.

Application of mesenchymal stem cells in corneal regeneration

Due to delicate its structure, the cornea is susceptible to physical, chemical, and genetic damages. Corneal transplantation is the main treatment for serious corneal damage, but it faces significant challenges, including donor shortages and severe complications. In recent years, cell therapy is suggested as a novel alternative method for corneal regeneration. Regarding the unique characteristics of Mesenchymal stem cells including the potential to differentiate into discrete cell types, secretion of growth factors, mobilization potency, and availability from different sources; special attention has been paid to these cells in corneal engineering. Differentiation of MSCs into specialized corneal cells such as keratocytes, epithelial and endothelial cells is reported. Potential for Treatment of keratitis, reducing inflammation, and inhibition of neovascularization by MSCs, introducing them as novel agents for corneal repairing. In this review, various types of MSCs used to treat corneal injuries as well as their potential for restoring different corneal layers was investigated.