Guest editorial: emergent themes from second annual symposium on regenerative rehabilitation, Pittsburgh, Pennsylvania.

INTRODUCTION Regenerative medicine advances hold the potential to drive dramatic progress in the prevention and treatment of individuals with a host of acute and chronic pathologies. Regenerative medicine is "an interdisciplinary field of research and clinical applications focused on the repair, replacement or regeneration of cells, tissues or organs to restore impaired function resulting from any cause, including congenital defects, disease, trauma and ageing" [1]. With return to normal activities of daily living as the ultimate goal of these biological therapies, it is clear that regenerative medicine is tightly intertwined with rehabilitation, which also involves the optimization of function and performance. As regenerative medicine approaches increasingly permeate medical practice, important questions arise about the development of adjunct clinical protocols that will maximize the therapeutic benefit of these technologies: Does the initiation of rehabilitation protocols following transplantation of biological scaffolds or cells enhance or hinder functional efficacy of the technology? If a rehabilitation protocol is initiated following administration of a biological therapy, as is likely to occur in a clinical setting, what is the optimal timing and dosing? Finally, how can basic science discoveries be most efficiently translated such that they may guide the development of targeted rehabilitation programs to promote tissue healing? THEORETICAL PREMISE FOR REGENERATIVE REHABILITATION It is increasingly recognized that mechanotransduction, or the conversion of a mechanical stimulus to chemical activity, plays an important role in dictating molecular, cellular, and tissue responses. Mechanotransductive pathways may be initiated by stretch, exercise, or electrical stimulation, indicating that the application of rehabilitation could dictate stem cell behavior and, as such, tissue regenerative potential. There is mounting evidence to suggest that, like endogenous stem cells, donor stem cells are amenable to the influences of the dynamic microenvironment [2-5]. The time is right to better understand the potential synergy between rehabilitation and the development of biological therapies. Such an understanding should clearly be rooted in collaborative investigations at the early stages of technology conceptualization and development so that the transition to the clinic may be smooth and efficient [6]. Regenerative rehabilitation may be defined as the integration of principles and approaches in rehabilitation and regenerative medicine with the ultimate goal of developing innovative and effective methods that promote the restoration of function through tissue regeneration and repair. While interdisciplinary research and practice is desirable, few opportunities are available to bring together scientists and clinicians working in these two disparate fields. With this in mind, the Second Annual Symposium on Regenerative Rehabilitation, organized by the University of Pittsburgh Medical Center Rehabilitation Institute; the McGowan Institute for Regenerative Medicine; the School of Health and Rehabilitation Sciences at the University of Pittsburgh; and the Palo Alto Department of Veterans Affairs (VA) Rehabilitation Research and Development Center for Tissue Repair, Regeneration, and Restoration, was held on November 12-13, 2012, in Pittsburgh, Pennsylvania. The regenerative rehabilitation symposium was designed to cross disciplinary boundaries in order to create a unique forum where stakeholders in the field of regenerative medicine could interact with rehabilitation clinicians and scientists to discuss the current and future landscape of the field. The specific objectives of the 2012 event, as summarized in this editorial, were (1) to catalyze the development of novel interactions and research directions among researchers, clinicians, and students conducting research in regenerative medicine and/or rehabilitation; (2) to determine barriers in the development of regenerative rehabilitation approaches; (3) to identify practical methods to overcome existing barriers; and (4) to introduce the concept of regenerative rehabilitation to graduate students, medical students, and medical residents in the rehabilitation field with the goal of inspiring the next generation of clinicians and scientists to embrace innovative technologies and to incorporate those technologies in their nascent clinical practices and research programs. …