Cartilage Regeneration and Stem Cell

Denis Evseenko, MD, PhD, bridges studies of early embryogenesis and stem cell biology to clinically relevant application of stem cell and small-molecule-based therapies. Current work addresses an unsolved question in the skeletal biology: What are the cellular and molecular components of the “niche” required for the long-term maintenance of cartilage-committed progenitors capable of differentiation into articular chondrocytes?

Recently, his research group defined the developmental progression through which primordial mesenchymal cells commit to the chondrocyte lineage in vivo. Based on these findings, his research group now focuses on developing novel translational pluripotent stem cell and small-molecule-based approaches for articular cartilage and bone regeneration. His laboratory is actively using pre-clinical in vivo models of cartilage and bone injury and repair. Visit the Evseenko Lab website. More specific information regarding current studies of note follows.

Here is a brief description of a study on the Kappa opioid receptor agonist as a potential joint protective therapy in osteoarthritis telling what it is and why it is significant.

The medication activates the kappa opioid receptor (KOR), which binds to opioid-like compounds in the central and peripheral nervous systems to alleviate pain, resulting in targeted pain relief with a reduced risk of addiction. Previous research shows that some opioids that selectively activate only KORs relieve pain locally at the site of injury without crossing the blood brain barrier and inducing substance dependency, whereas commonly prescribed opioids that target other receptors in the brain are more addictive. In this study, lead author Alexander Weber, MD, sports medicine physician and orthopaedic surgeon with Keck Medicine, and corresponding author Denis Evseenko, MD, PhD, vice chair for research and associate professor of orthopaedic surgery at the Keck School of Medicine of USC, locally administered a kappa opioid into arthritic rodent knees and measured the progression of the disease in their joints. The researchers confirmed that the medication effectively alleviated pain, however findings also suggest that the medication prevented the loss of cartilage, the connective tissue between the joins that pads bones, and slowed the progression of osteoarthritis. Arthritis affects nearly a quarter of adults in the United States, many of whom take addictive opioids to manage their pain. The implications of this study may someday alter how we provide orthopaedic care to significantly reduce the number of patients experiencing long-term pain and addiction.

More can be seen at the HSC News site.

Another study of interest concerns the Pluripotent stem cell-based bioimplants for restoration of articular cartilage.

Articular cartilage injury and the lack of cartilage regeneration often lead to osteoarthritis, characterized by the degradation of joints, including articular cartilage and subchondral bone. Current treatments for cartilage lesions, cartilage degeneration and arthritis are mostly palliative, with most efforts focused on reducing inflammation and pain. Drugs like ibuprofen reduce pain and inflammation, but they do not induce regeneration of tissue. Stem cell therapies are designed to regenerate the tissues, to restore them to as close to normal as possible. After years of painstaking research funded by the California Institute of Regenerative Medicine (CIRM), USC team led by Drs Evseenko MD., PhD and Frank Petrigliano MD, have pioneered a stem cell therapy for what are called focal cartilage lesions.

The team has developed a patch infused with stem cells with strong reparative potential and ability to integrate and rebuild damaged joint tissues by providing new supply of juvenile cartilage cells naturally lacking in adults. This biomimetic stem cell patches called Plurocart are nearing the clinical trial stage. Therapeutic intervention at the early stage, when the lesion is contained and most of the joint tissues are healthy, is likely to delay the onset of osteoarthritis and perhaps completely eliminate the need for total joint replacement. Surgeons place the patch on a lesion where the stem cells are intended to create new cartilage cells. The team has successfully presented this new therapy to the FDA and has recently entered a partnership with GMP facility to manufacture clinical grade implants for first in man clinical trial.

More information about the Evseenko lab is available at HSC News.

Thomas Lozito, PhD, joined our department on Feb. 1, 2019. Lizards are the closest relatives of mammals that exhibit the amazing ability to regrow amputated tails. In doing so, lizards regenerate several tissues including cartilage, peripheral nerves, spinal cords, muscle and skin. The Lozito Lab examines wound healing in lizards and mice — including commonalities, differences, and the underlying causes of varying outcomes — for the purpose of improving human regeneration. Visit the Lozito lab site at: https://lozitolab.usc.edu/.

Thomas Lozito, PhD, is attempting to answer the question “Why can’t mice regenerate tails like lizards?”. From lizard species capable of spontaneously regrowing amputated tails to mammals that favor scarring over new tissue growth, amniotes include a diverse range of regenerative potentials. The Lozito Lab seeks to determine the cellular and molecular determinants of this diversity in tail amputation regenerative capacities with the goal of improving an organism’s natural wound healing abilities. Our ten-year-goal is to create a mouse capable of spontaneously regrowing an amputated tail like a lizard. We have established research colonies of specialized lizard species exhibiting a gradient of regenerative capabilities, as well as tools for manipulating these capabilities in vivo. Some of these lizard species complete the full tail regrowth program, while other species fail to reach specific milestones along the process. The vision for our research program involves using these select lizard species as “stepping stones” for bridging the gap in wound healing capabilities between non-regenerative mice and fully regenerative lizards. If we can sequentially manipulate the mouse to match the healing processes achieved by the next most similar lizard species along the gradient, the anticipated result will be a mouse line with full regenerative capabilities. For example, one of the earliest milestones in tail regeneration involves activation of specific populations of spinal cord neural stem cells (NSCs). NSC activity varies greatly among amniotes, and regenerative species exhibit a cell state not achieved by non-regenerative species. During another milestone, regenerative lizard species reprogram their own connective tissue stem cells known as blastema cells capable of differentiating into new tail tissues. Non-regenerative species do not achieve sufficient reprogramming depth, resulting in poor-quality cells with hindered differentiation capacities that favor scar formation. We believe that differences in NSC and blastema cell signaling account for divergent regenerative abilities among species, and “correcting” these differences will enhance tail regrowth in non-regenerative organisms. The overall goals of this research are to identify the specific signaling activities responsible for inducing tissue regeneration, and influence these regenerative signals to improve amputation healing in naturally non-regenerative organisms. The successful completion of this research program will answer several long-standing questions central to the field of regeneration and enhance our understanding of differentiation processes involved in adult amniote regeneration. The principles and experience gained from completing such a milestone can contribute to the knowledge base for improving the healing abilities of non-regenerative organisms, including humans.

Skeletal Muscle Regeneration

Albert E. Almada, PhD is investigating one of the greatest mysteries in muscle regenerative biology—how stem cells rebuild functional muscle tissue after traumatic injury. His multidisciplinary team integrates state-of-the-art experimental and bioinformatic approaches to study this biological phenomenon at the molecular, cellular, and organ level in various animal models and in humans.

Recently, Dr. Almada discovered a new “Super-Healing” gene regulatory program, and he is exploring the biology and therapeutic potential of these pro-regenerative molecules in pre-clinical mouse models. Dr. Almada’s long-term goal is to translate his basic science discoveries into effective stem cell-based therapies that restore muscle function to injured athletes, wounded soldiers, the elderly, and patients suffering from degenerative muscular pathologies. Visit Dr. Almada’s Lab site.

Bone Repair and Stem Cell/Gene Therapy

Jay R. Lieberman, MD, is a pioneer in the development of regional gene therapy to enhance bone repair. A number of difficult bone repair scenarios exist for which no consistently satisfactory solution is available, including: fracture nonunion, acute fractures with extensive bone loss, revision total joint arthroplasty and pseudarthrosis of the spine.

Traditionally, autologous bone graft has been the gold standard but, with a limited supply of this bone, concerns remain regarding the morbidity associated with graft harvest. Recombinant bone morphogenetic proteins (BMPs) are FDA-approved for use in spinal fusion and treatment of fresh tibial fractures. However, BMPs have had mixed success in humans and are associated with side effects including soft tissue edema and heterotopic ossification.

Orthopaedic surgeons have long sought alternative tissue engineering strategies to enhance bone repair. Lieberman aims to develop regional gene therapy using transduced bone marrow cells as a comprehensive tissue-engineering strategy to enhance bone repair. The Lieberman laboratory was the first to successfully heal a critical-sized femoral defect using bone marrow cells genetically manipulated to overexpress BMP. Recently, his group developed a “same day” gene therapy strategy to facilitate clinical adaption of this regimen. Bone marrow cells were transduced with a lentiviral vector containing the cDNA for BMP-2 and successfully healed a large bone defect. The laboratory is now assessing the biologic potential of genetically manipulated human bone marrow cells and adipose-derived stem cells in order to move this research closer to the clinic.

Spine Research – Jeffrey C. Wang, MD

Low back and neck pain are leading causes of disability worldwide. The primary focus of Jeffrey C. Wang MD is understanding the biology and mechanisms of various spine pathologies using basic science models and clinical research. In vitro and in vivo studies include projects on spinal fusion and bone formation, and intervertebral disc degeneration. Osteobiologics are one of the key interests, they serve as a framework to reinforce and support bone growth after spine fusion. Our studies utilize animal models of lumbar posterior fusion to analyze various graft materials, assess bone remodeling and compare what components (stem cells vs. growth factors) drive bone formation. Clinical questions are intertwined with both our animal and in vitro models. Certain clinical aspects such as risk factors (e.g. nicotine) are implemented in our cell models to better understand the changes in molecular mechanisms of bone formation.

We apply our expertise in the field of tissue engineering, biomarkers and mechanobiology to look at the potential of matrix markers, and stem cells to drive disc regeneration. Our animal models of disc degeneration use minimally invasive methods to create degenerative cascades and test different molecules as promotors of regeneration. Close interactions within the Department of Orthopaedic Surgery, as well as with other research centers and spine societies, enable extensive collaboration on a range of projects.