It is with profound sadness that we report the passing of Arnold Caplan, Ph.D. Dr. Caplan was an ICRS member from 2005 and was an ever present faculty participant at most of our summit and world congress meetings where he always asked the most scintillating questions leading to some of the most memorable and entertaining scientific debates I can recall. Dr. Arnold I. Caplan, 82, of Cleveland, passed away peacefully on Jan. 10, 2024, with his family lovingly by his side.
A distinguished scientist and pioneer, Dr. Caplan left an indelible mark on the field of regenerative medicine during an illustrious career spanning over five decades. Born Jan. 5, 1942, in Chicago, Dr. Caplan earned his Bachelor of Science degree in chemistry from the Illinois Institute of Technology and his Ph.D. from the Johns Hopkins University School of Medicine. Joining Case Western Reserve University in 1969, he steadily rose through the academic ranks, becoming a professor in 1981 and dedicating an impressive 54 years to the institution.
A pivotal moment in his career came with the isolation of human Mesenchymal Stem Cells (MSCs) from adult bone marrow, establishing the conceptual and technical foundation for subsequent global studies. In 1992, he founded Osiris Therapeutics, Inc., commercializing the technology, which later lead to numerous clinical trials worldwide. He is widely recognized as the father of both basic science and clinical therapeutics of adult Mesenchymal Stem Cells (MSC’s). His initial work focused on the “Mesengenic process” whereby MSC’s could be preferentially differentiated into the numerous tissues of the mesodermal lineage. He later made the brilliant discovery that these cells also exhibited regenerative properties and updated his theory and renamed them “Medicinal Signaling Cells”. Dr. Caplan’s demonstrated the innate ability of MSC’s to modulate the immune system; inhibit both programmed cell death and scar formation; to stimulate blood-vessel formation; and to promote the growth of tissue-specific stem cells. His work has impacted studies and treatment of various human diseases ranging from multiple sclerosis and osteoarthritis to spinal cord injuries to cancer.
Dr. Caplan’s warmth and mentorship touched the lives of countless others he trained – shaping the lives of over 150 researchers with his intellect and guidance. His passion extended to sharing his expertise through influential courses, fostering scientific collaboration globally. He was also honored with many awards including The Marshall R. Urist Award, The Tissue Engineering and Regenerative Medicine International Society Lifetime Achievement Award, and the Case Western Reserve University Faculty Innovator Award. He has over 400 published papers and 20 patents. His contributions shaped the landscape of regenerative medicine.
I recall fondly being at numerous meetings such as the ORS, AAOS, and ICRS and whenever Arnie got up to ask a question it was always provocative and insightful; he always saw in science what others missed. I would call him regularly for his advice on numerous scientific topics and he always was happy to help and in typical Arnie fashion would share his wisdom and make me laugh. To say he was a positive force of nature is an understatement. When I was finishing up my post-doc he sought to recruit me to Case western, which at the time was one of the epicenters of orthopedic research along with Victor Goldberg, MD [Orthopedic surgery] and had formed the musculoskeletal research center. While I did not go to Case due to family issues I often think, as in the Robert Frost poem- the road not taken, how my career trajectory would have been if I had worked with Dr. Caplan. Beyond the laboratory, Arnold was a devoted husband, father, grandfather, and friend, creating a legacy that extends far beyond scientific achievements. His love for cooking, walks, and deep, meaningful conversations (which often became debates) will be missed by many. He leaves behind a tapestry of cherished memories, instilling values of love, wisdom, and warmth in the hearts of those who knew him.
Arnold I. Caplan is survived by his loving wife of 58 years, Bonnie; his two children, Aaron (Tami) Caplan and Rachel (David) Uram; six wonderful grandchildren, Josh, Andrew and Brian Caplan, and Lyla, Sam, and Bella Uram; and his brother, Herbert (Barbara) Caplan. He lives on through the countless lives touched by his pioneering work and unending love for family and friends.
Daniel A. Grande, PhD., ICRS President 2023-2025
on behalf of the International Cartilage Regeneration & Joint Preservation Society
