Mesenchymal Stem Cells

In the summer of 1964, I took a graduate pathology course for non-MDs given by Professor Guido Mino at Harvard Medical School. Dr Jerry Gross gave a 2-hour lecture in that course which went from the chemistry and structure of collagen up through the collagenase-mediated destruction of collagen during tadpole tail resorption and metamorphosis. This lecture changed my life forever and set the tone of my thinking and research by demonstrating the continuum of molecules through the control of biological phenomena as seen through the eyes of a biochemist and developmental biologist. In 1967, I started a postdoctoral fellowship with Nathan O. Kaplan, PhD, at Brandeis University where I met and joined the lab of Edgar Zwilling, PhD. Professor Zwilling was a renowned embryologist and developmental biologist1,2 who taught me about these subjects as I started studying the differentiation capacity of undifferentiated embryonic chick limb mesodermal cells in culture.3 These cells were mesenchymal stem cells (MSCs) that have the capabilities to differentiate in vitro into a number of mesodermal phenotypes by controlling the initial seeding density in culture and the medium additives and conditions.4-6 Thus, I was able to study the molecular control of embryonic chick limb cell differentiation and limb development7 in ways complementary to those described by Dr Gross 5 years earlier. This was the start of my MSC journey and experimental exploits.