Similarly, the pores of scaffold are also important cue

Similarly, the pores of scaffold are also important cue. direct reprogramming and biomaterials-guided stem cell differentiation are summarized with the addition of the up-to-date progress on biomaterials for direct reprogramming. Keywords: Direct reprogramming, Stem cell, Surface, Growth factors, ECM, Gene delivery Background Regenerative medicine 10-Undecenoic acid has been getting the spotlight in the medical science as a solution of intractable diseases. Especially stem cell therapy has great potential to cure many injuries and diseases. Stem cells have the ability to continuously divide and differentiate into various kinds of cells or tissues [1]. The main types of stem cells are embryonic stem cell (ESC), adult stem cell (ASC), and induced pluripotent stem cell (iPSC). ESC is derived from the inner cell mass of a blastocyst. It has pluripotency to 10-Undecenoic acid be expanded unlimitedly and can differentiate to all three germ layers. But it is hard to get ESC and furthermore there is a severe ethical issue [2]. On the other hand, ASC, also called somatic stem cell, comes from the body after embryonic development, such as bone marrow, umbilical cord, adipose tissue, and blood cell. The source of ASC is more affordable than ESC, and ASC have less ethical issues compared to ESC [3, 4]. However, ASC is multipotent, not pluripotent, so the differentiation ability is less than ESC [5]. For overcoming the limitation of ESC and ASC, iPSC has been developed. iPSC is reprogrammed human cell by some defined factors to generate the patient-specific pluripotent cell lines [6, 7]. Yamanaka showed that iPSC can be generated using only four transcription factors, Oct4, Sox2, Klf4, 10-Undecenoic acid and c-Myc [7]. iPSC can be obtained easily and has pluripotency to differentiate into any one of three germ layers, meaning that iPSC is a powerful regenerative medicine tool right away. However, iPSC also has several obstacles for practical applications. First of all, iPSC is not safe for clinical applications in its current state [8, 9]. Commonly, viral vector systems are used to generate iPSC, which might integrate into the host DNAs. More importantly, iPSC has risk to form tumors when transplanted in vivo because of the use of oncogene in the reprogramming process. Also, the efficiency of generating iPSC has been too low yet. Direct reprogramming is a new approach to overcome diverse problems of stem cell therapies. Direct reprogramming means that reprogramming the somatic cell into a desired patient specific cell directly without passing through the pluripotent stem cell stage [10]. This method has 10-Undecenoic acid a low risk about epigenetic remodeling and tumor formation. Also, it is more efficient and can be accomplished Akt1 in an economy of time. In this review, direct reprogramming into various cell lineages will be introduced. Also biomaterials for affecting stem cell differentiation will be presented, and finally biomaterials to increase the efficiency of direct reprogramming will be introduced. Generally, direct reprogramming is also called transdifferentiation. Direct reprogramming and transdifferentiation are usually used as the same meaning, but exactly, direct reprogramming means the changing fate of somatic cell without dedifferentiation process and transdifferentiation means that less differentiated cell of certain lineage differentiates into other cell of similar lineage [11]. Here, the term direct reprogramming will be used as the same meaning with transdifferentiation. Direct reprogramming The general strategy for direct reprogramming uses transcription factors depending on the lineage of target. Most common cell source is the fibroblast from mouse or human. Here, recent examples of direct reprogramming will be discussed according to the final target cell type: Neural cells, cardiomyocytes and hepatocytes. Direct reprogramming to neural cells Neurodegenerative disorders, such as Alzheimers disease, Parkinsonss disease and Huntingtons disease, have high lethality but there is no obvious cause and no effective medical treatment. Common symptoms of neurodegenerative disorders are continuously dying neural cells through necrosis.