Advances in Regenerative medicine

PREFACE In order to better introduce this book, it is important to define regenerative medicine as this field is built through a combination of multiple elements including living cells, matrix to support the living cells (i.e. a scaffold), and cell communicators (or signaling systems) to stimulate the cells, and their surrounding environment to grow and develop into new tissue or organ. Indeed, regenerative medicine is an emerging multidisciplinary field involving biology, medicine, and engineering that is likely to revolutionize the ways we improve the health and quality of life for millions of people worldwide by restoring, maintaining, or enhancing tissue and organ function. Even if the origins of regenerative medicine can be found in Greek mythology, as attested by the story of Prometheus, the Greek god whose immortal liver was feasted on day after day by Zeus' eagle; many challenges persist in order to successfully regenerate lost cells, tissues or organs and rebuilt all connections and functions. In this book, we will cover few aspects of regenerative medicine highlighting major advances and remaining challenges in cellular therapy (including cell communicators) and tissue/organ engineering. CELL REPLACEMENT THERAPY The types of cells that are used are dependent on the type of tissue that needs to be repaired. Several cells have been suggested as suitable for cellular therapies: i.e. embryonic stem cells (ES), induced pluripotent stem cells (iPS); somatic stem cells from fetal or adult tissues. The potential use of fetal tissue or differentiated embryonic stem cells from allogenic sources suffer limitations due to tissue availability, ethical issues or safety concerns. On the contrary, adult somatic stem cells can be used in autologus graft procedure, avoiding patient’s immunosuppression. In this book, several chapters will be developed on stem cell applications in regenerative medicine focusing on several organs or tissues like brain, heart, liver or retina. CELL COMMUNICATORS. The circulatory system is involved in the transport of a wide variety of biological molecules and cells and can be considered as the body's basic communication system. Cell communicators act as a signaling system, which stimulates the cells into action. In some cases those communicators could lead cells to integrate damage tissues and rebuilt lost connections, however, some signals could also induce cellular stress responses conducting to cell death. Few of those aspects will be directly address in this book. TISSUE ENGINEERING OR …WHERE BIOLOGY MEETS ENGINEERING. All cells within tissues are separated and interlinked by a matrix or structure. The consistency of the matrix may vary from a liquid, as in blood; to semi-solid, as in cartilage; to a solid, as in bone. Tissue engineers either implant cells into a matrix or create the proper conditions for the living cells to build their own three dimensional matrix. Such a matrix provides the structure that supports the cells and creates the physiological environment for them to interact within the host tissue. The success or failure of an implant material in the body depends on a complex interaction between a synthetic ‘foreign body’ and the ‘host tissue’, which involve not only biological, but also mechanical, physical and chemical mediated factors. The latest advance in tissue engineering will be developed in this book underlying many challenges that remain pending in this field