Articular cartilage has a limited capacity for self-repair. Untreated injuries of cartilage may lead to osteoarthritis. This problem demands new effective methods to reconstruct articular cartilage. Mesenchymal stem cells (MSCs) have the proclivity to differentiate along multiple lineages giving rise to new bone, cartilage, muscle, or fat. This study was an animal model for autologous effects of transplantation of MSCs with a collagen-poly(vinyl alcohol) (PVA) scaffold into full-thickness osteochondral defects of the stifle joint in the rabbit as an animal model. A group of 10 rabbits had a defect created experimentally in the full thickness of articular cartilage penetrated into the subchondral space in the both stifle joints. The defect in the right stifle was filled with MSCs/collagen-PVA scaffold (group I), and in the left stifle, the defect was left without any treatment as the control group (group II). Specimens were harvested at 12 weeks after implantation, examined histologically for morphologic features, and stained immunohistochemically for type-II collagen. Histology observation showed that the MSCs/collagen-PVA repair group had better chondrocyte morphology, continuous subchondral bone, and much thicker newly formed cartilage compared with the control group at 12 weeks post operation. There was a significant difference in histological grading score between these two groups. The present study suggested that the hybrid collagen-PVA scaffold might serve as a new way to keep the differentiation of MSCs for enhancing cartilage repair.

Neural differentiation of stem cells is an important issue in the development of the central nervous system. Different methods such as chemical stimulation with small molecules, scaffolds, and microRNA can be used for inducing the differentiation of neural stem cells. However, microfluidic systems with the potential to induce neuronal differentiation have established their reputation in the field of regenerative medicine. Organization of the microfluidic system represents a novel model that mimics the physiologic microenvironment of cells among other two-and threedimensional cell culture systems. The microfluidic system has a patterned and well-organized structure that can be combined with other differentiation techniques to provide optimal conditions for neuronal differentiation of stem cells. In this review, different methods for effective differentiation of stem cells to neuronal cells are summarized. The efficacy of microfluidic systems in promoting neuronal differentiation is also addressed.

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Objective The local regulations for conducting experimental and clinical cell therapy studies are dependent on the national and cultural approach to the issue, and may have many common aspects as well as differences with the regulations in other countries. The study reflects the latest national aspects of cell therapy in Iran and relevant regulations. Methods The following topics are discussed in the article including sources of cell harvest, regulations for cell disposal, stem cell manufacturing, and economic aspects of stem cell, based on current practice in Iran. Results All cell therapy trials in Iran are required to strictly abide with the ethical codes, national and local regulations, and safety requirements, as well as considering human rights and respect. Adherence to these standards has facilitated the conduct of human cell therapy trials for research, academic advancement, and therapy. Conclusions The cell therapy trials based on the aforementioned regulations may be assumed to be ethical and they are candidates for clinical translations based on safety and efficacy issues.