35 St George St
Toronto, ON M5S 1A4
Novel Roles of Tendon/Ligament in Bone and Joint Formation: Beyond Moving Skeleton
Jerry Feng, PhD
Professor, Department of Biomedical Sciences, Texas A&M University College of Dentistry
Our understanding of skeletal biology in the following fundamental areas are limited: 1) Cartilage and bone have been considered to be exclusively formed by their own cells; 2) The sole function of tendon and ligament (two extremely similar, tough, fibrous connective tissues, which are simply described as tendon in this proposal) has been presumed to be limited to transmitting muscle forces to control body movement and stabilize joints; 3) Loss of bone mass in astronauts due to space flight or gain of bone mass due to exercise are thought to be indirect effects of altered mechanical loading by muscle; and 4) Clinically, cartilage trauma or diseases (such as osteoarthritis) cannot be repaired by their own cells. Common procedures for restoration of joint function are knee or hip replacement with metal prostheses. Moreover, in large bone trauma cases (such as war casualties, car accidents, or removing bone tumors) patients’ bodies cannot provide enough bone graft for repair.
Recently, our lab has made the following new findings, which will be present in this seminar:
- Identification of an obvious but largely ignored difference of bone structures between tendon attachment sites (rough with many bone ridges) and the periosteum-formed bone surfaces (smooth and even), indicating two different precursor cell sources;
- Discovering a new type of tendon, referred to as “mini-range tendon” (containing a few tendon cells), that along with long-range tendon, forms a massive interface zone (rich in mixtures of tendon, cartilage, and bone ECM proteins); and that there is a lack of periosteal layer between the interface and its overlaying bones, suggesting that the tendon derived interface cells may directly contribute to a new type of bone that is distinct from the periosteum-derived bone in cell density, distribution pattern and protein expression levels, and highly dependent on mechanical forces;
- A direct contribution of tendon/ligament cells to joint expansion; and
- Potential application of autograft tendon/ligament in bone and cartilage repair
Dr. Jerry Feng was trained as a physician in China, and he obtained his PhD from the University of Connecticut. His postdoctoral fellowship training took place at the University of Michigan and the University of Texas Health Science Center, San Antonio. Currently Dr. Feng is a full professor with tenure at the Texas A&M College of Dentistry. His primary duty is Research and Scholar activity. His expertise and background include bone, cartilage and tooth research using both animal models (loss of function, gain of function, and mutation), and patient samples (such as osteoporosis, osteoarthritis and periodontitis), as well as the in vitro molecular research. He currently holds three R01s (two as PIs and one as Co-I). Dr. Feng has published 172 journal articles, 13 book chapters, 2 proceedings, and 6 gene sequences in his career, including ones appearing in Science, Nature Medicine, Nature Genetics, and PNAS. Based on Google Scholar, his citation indices are 15319 (All), 9343 (5 years) based on http://scholar.google.com/citations?user=0MJI52gAAAAJ&hl=en. A recent publication from Dr. Feng’s lab entitled “Chondrocytes Directly Transform into Bone Cells in Mandible Condyle Growth” was selected as the cover page of Journal of Dental Research (the foremost journal in Dentistry) 2015. His contributions to the sciences have led to awards and recognition from several scientific societies, including 1). the dental research community such as the William Gies Award (IADR 2005 and 2017); keynote speaker at the 2006 American Association for Dental Research annual meeting; the IADR Distinguished Scientist Award in 2011, and IADR-APR 2019 – Keynote Speaker); 2) the Bone & Mineral Society (Invited Speaker at the International Sun Valley Workshop on Skeletal Tissue Biology 2005, 2007; the Gordon Research Conferences on Small, Integrin-Binding Proteins 2005, 2007; the Gordon Research Conferences on Bones and Teeth 2007, 2014; the 2nd joint International Bone & Mineral Society 2009; Keynote Speaker Invitation to ANZORS 2018, Perth, Australia); 3) the American Society of Nephrology (Invited Speaker in 2008); and 4) the Association of Anatomists (Invited Speaker in 2005, 2008, 2014, and 2016). Included in the over 100 invited presentations, Dr. Feng gave two presentations at the Harvard Dental School (2010, and 2013), and two times in NIH/NIDCR (2011, 2014). Dr. Feng was also named an invited Visiting Professor in Australia two times: one at the University of Western Australia (2008), and the other at the Queensland University of Technology (2013).
Specifically, Dr. Feng’s published works made seminal contributions to our knowledge in:
1. Demonstration of the endocrine function of Osteocytes (secrete FGF23 and regulation of Pi homeostasis);
2. Discovery of a new disease, autosomal recessive hypophosphatemic rickets due to DMP1 mutations;
3. Demonstration of the key role of periodontal ligament (PDL) progenitor cells in alveolar bone formation (i.e., alveolar bone is mainly formed by progenitor cells in PDL), which explain why pulling out of teeth leading to alveolar bone loss;
4. Identification of the single ossification center in TMJ condylar ramus formation, in contrast to two ossification centers in long bone formation; and demonstrate that chondrocytes directly transformed into bone cells.
Dr. Feng’s ongoing works has made pivotal contributions to our knowledge in Bone Developmental Biology, and osteoporosis:
5. For over many decades, osteoblasts are considered as the cells building bone. His lab recently demonstrated that It is the osteocyte, but not the osteoblast, that builds mineralized bone;
6. For a long time, it is widely believed that an imbalance of osteoblasts and osteoclasts leads to development of Osteoporosis. His recent work revealed that osteocytes play a dual role in bone remodeling; and that a defect in osteocyte structure and function results in osteoporosis;
7. Identification of the 3rd types of bone beyond endochondral bone and intramembranous bone; and discovering the direct contribution of tendon/ligament in joint expansion.
As a senior professor and the Associate Head of the Department of Biomedical Sciences, as well as the Assistant Dean for Research at College of Dentistry, Dr. Feng has closely collaborated with faculty members at the school, and helps junior faculty members with their grant applications through brainstorming activities.
Teaching and supporting Graduate Students and Dental Students with their research are Dr. Feng’s priorities, and he spends ~30% of his time with students on education, research topic selection, editing their thesis/manuscripts/lab reports/presentation drafts. Dr. Feng has trained numerous MS and PhD students, as well as postdoctoral fellows, from different countries. Many of trainees have won scientific and training awards, including Young Investigator Awards, F32, K99, and K22. Four of them have been moved up to faculty positions in US Universities and obtained R03 and R01 grants. Many of them returned to their own countries and were promoted to Associate Deans for Research, Department Chairs and faculty members. Of note, two of Dr. Feng’s PhD trainees won the ASBMR President’s Award (American Society of Bone Mineral Research), in 2004 and 2015. This award is awarded for the highest ranking abstract by a student; a $1,500 honorarium with one award is given per year.