Most human tissues do not regenerate spontaneously. This is why the development of biotherapies with stem cells represents promising alternatives. The annual expenses linked to these innovative treatments is estimated to more than 100 billion euros over the next 10 years.

Among possible medium-term therapeutic applications are, cardiac insufficiency, preparation of small diameter arteries, treatment of atherosclerosis, bone repair, cartilage defects, burns, diabetes, liver or bladder regeneration, and neurodegenerative disorders. This concept of regenerative medicine is an emerging multidisciplinary field involving surgery medicine, biology, chemistry, mechanics and engineering that can be defined as «the way to improve the health and quality of life by restoring, maintaining, or enhancing tissue and organ functions».

Cell therapy and regenerative medicine are taking a growing place as innovative treatments for the replacement or repair of aged or dead cells or tissues. Indeed many organs are progressively and irreversibly damaged during aging, or after severe degenerative diseases, thus finally affecting their function. This process leads to an alteration of the patient’s life quality, and often threats its survival. Regenerative medicine, as a new therapeutic strategy, aims at restoring defective organs by several biological tools or processes, especially the use of mesenchymal stem cells. Regenerative medicine relies on multi-disciplinary approaches of cell and tissue engineering at the cross road of biological and engineering sciences involving a close partnership between biologists, physico-chemists, biomechanics, clinicians, thus providing a continuum from basic science to the clinics. One of the best synergy examples between cell biology and engineering is the extended use of the 3D-bioprinting which helps in the efficient building of organs such as liver or cartilage.

Since the 1960s and the therapeutic use of hematopoietic stem cells of bone marrow origin, there has been increasing interest in the study of undifferentiated progenitors that have the ability to proliferate and differentiate in different tissues. Although, autologous cells were previously chosen as the best candidates, these cells are generally not easily available. They are frequently in a pathological state and expansion cannot be performed for all tissues and organs. This explains the growing interest in stem cells that are produced during the development of the embryo, then of the fetus and finally in adult tissues and organs. Different stem cells with different potential can be isolated and characterized (totipotent or mesenchymal of different origins, especially those present in tissues…). It is undeniable that bone marrow, adipose tissue or Wharton’s Jelly stem cells are of potential interest for clinical applications because they are easily separated and prepared, and no ethical problems are involved in their use.

This multidisciplinary approach allows deciphering and better understanding the molecular mechanisms of stem cells differentiation as well as their immunological properties. This led to significant advances in the cells function and their potential use in clinics, especially epigenetics that seems to play an increasing role in the regulation of these processes. More recently the extracellular vesicles originated from stem cells appeared as a promising alternate for their use for cell-free therapy. This will contribute to the possibility to repair or reconstruct several types of tissues or organs (cartilage, bone, tendons, liver, vascular, dental or nerve tissues…) whose function has been altered by diseases or aging, or to use as new drugs for pathologies such as cancers or degenerative diseases.

A large number of potential methods exists for each tissue or type of therapy. For example, the amounts of tissue produced by in vitro cultures are generally higher when three-dimensional porous supports are used when compared with monolayer cultures. Moreover, mechanical stress influences the differentiation of cells. Such changes are now considered as critical for understanding pathological mechanisms (osteoarthritis, inflammation, atherosclerosis, etc.). Biotherapies have also major applications in the field of cancer therapies (i.e., leukemia, melanoma, prostate cancer, etc.).

However, and despite the promise of embryonic stem cells, in many cases, adult stem cells provide a more interesting approach to clinical applications. In other respects, some lineages of adult stem cells are capable of greater plasticity than those of their origin tissue. Nowadays, mesenchymal stem cells represent an enormous potential value for regenerative medicine. During the last 10 years, these multipotent cells have generated considerable interest. They showed to escape allogeneic immune response and to be capable of immunomodulatory activity. These properties may be of a great interest for the future of regenerative medicine, but today it is probably better to consider mesenchymal stem cells as a mixed population of progenitors rather than as homogeneous stem cells.

The regeneration of tissues is and will remain a challenge for the future development of cell therapy and tissue engineering. Many problems remain to be solved and scientific and technical knowledge is lacking to lead to the development of innovative strategies to facilitate cell differentiation, increase the yield of cells and ensure a standardized production, overcome the risks of teratogenic effects and/or immune reactions, enable grafting via direct cell or biotissue transplantation and avoid legal issues involved in national regulations.

The 9^th France-China Symposium on “Stem cells and Regenerative Medicine” was held in Strasbourg (France), 2–4 October 2019 at the Faculty of Dental Surgery. Strasbourg, located in the east part of France, is the capital of Alsace and one of the of Europe capitals by the presence of the Europe Parliament and other European institutions. It is well known by its University, Research Centers and Medical University Hospital, and welcomes several Nobel prizes.

The aim of this symposium was to provide researchers, clinicians and students a comprehensive up-to-date overview of stem cells and potential medical applications in cellular and tissue engineering for the treatment of various chronic diseases. The main objective was to bring scientists together from various disciplines and experiences and to discuss the recent advances in the use and applications of stem cells.

The Symposium was organized around three complementary themes introduced by eminent scientists renowned in their fields; cell, tissue engineering, and clinical applications. Important complementary aspects such as ethic, and cell marketing were also presented.

This book puts together the manuscripts from the presented lectures of the Symposium which illustrates the challenges and the recent progress performed on the characterization of stem cells.

The Guest Editors would like to thank all participants and authors for their valuable cooperation, contribution and efforts. The significant support of the Region Grand Est is gratefully acknowledged, together with CNRS, University of Lorraine and University of Strasbourg.

Daniel George

CNRS-UMR 7357, ICUBE Laboratory, University of Strasbourg, France

Jacques Magdalou

CNRS-UMR 7365, Biopôle, Faculté de Médecine, 54500 Vandœuvre-lès-Nancy, France

Jean-François Stoltz

CNRS-UMR 7365, Biopôle, Faculté de Médecine, 54500 Vandœuvre-lès-Nancy, France