January 2019 – Clarissa Craft, PhD
Assistant Professor of Medicine
Dr. Craft completed her graduate work in cancer drug discovery at Northwestern University’s Feinberg School of Medicine in 2007. The same year, she joined the Department of Cell Biology and Physiology at Washington University as a postdoctoral fellow in the laboratory of Dr. Bob Mecham. During her fellowship, Dr. Craft investigated extracellular matrix (ECM)-mediated regulation of TGFß within the skeleton. In 2012, Dr. Craft was promoted to Assistant Professor in the Department of Cell Biology and Physiology. Early in her independent career, Dr. Craft was funded by the American Diabetes Association to define the role of the ECM in adiposity and metabolic disease. During this time, she found that loss of a single ECM protein, MAGP1, was sufficient to predispose mice to metabolic syndrome (obesity and diabetes), pathologic bone marrow adipose tissue (BMAT) expansion, and bone fractures. The finding that diabetes was linked to bone fragility and altered BMAT adipocyte function led to a collaboration with Dr. Erica Scheller. In response to the success of their collaboration, in 2016 Dr. Craft transferred to the Division of Bone and Mineral Diseases to create a novel joint laboratory with Dr. Scheller which investigates the relationship between nerves and bone, with current emphasis on neuropathy and skeletal metabolism in diabetes. The lab’s research in bone marrow adiposity (BMA), diabetic neuropathy, and skeletal ECM were recently highlighted through oral presentations at the 2018 BMA Society meeting in Lille, France and the 2018 ASBMR meeting in Montreal, Canada. In her spare time, Dr. Craft enjoys spending time outdoors with her husband and children at their farm in Sullivan, Missouri.
For more information about Dr. Craft’s research interests, please visit the lab’s website:
May 2019 – David Brogan, MD, MSc
Assistant Professor of Orthopaedic Surgery
The Orthopaedic Nerve Research Lab is a collaborative effort between Dr. Christopher Dy and Dr. David Brogan. Over the past two years, the laboratory has been focused on translational and epidemiologic research regarding complex peripheral nerve injuries. Dr. Dy has received funding from the NIH to explore the utilization of qualitative research methods in describing the psychosocial effects of brachial plexus injuries on patients. His previous work has also focused on understanding the epidemiology of these severe injuries to better understand injury patterns.
Dr. Brogan’s focus is on translational research to better improve the diagnosis of nerve injuries in the operating room. He has received funding from the American Foundation for Surgery of the Hand to evaluate the application of laser Doppler blood flow technology through the diagnosis of peripheral nerve crush injuries. The lab also works closely with Dr. Samuel Achilefu in the Optical Radiology Lab. The current work explores the utilization of near-infrared optical probes to better understand the cascade and sequence of events that occur surrounding a peripheral nerve injury. Our hope is to eventually develop tools that can be utilized with existing equipment in the operating room to assist with image-guided nerve surgery. The lab also has ongoing collaborations with the Department of Genetics as well as the Department of Neurosurgery. Dr. Dy and Dr. Brogan are committed to continuing their work to hopefully improve the diagnosis of nerve injuries, as well as mechanisms for better surgical treatment and the aftercare of patients affected by these life-altering injuries.
July 2019 – Brian Finck, PhD
Research Associate Professor of Medicine
The Finck Lab is interested in understanding the regulation of intermediary metabolism in a variety of tissues, including skeletal muscle. For many years, we have been interested in the lipin family of proteins (lipin 1, 2, and 3). Lipins are intracellular proteins that primarily act as lipid phosphatase enzymes in the pathway of triglyceride synthesis. Interestingly, these proteins can also translocate to the nucleus to directly regulate gene expression by interacting with DNA-bound transcription factors that control the expression of metabolic enzymes. Thus, lipin proteins can control metabolism at multiple regulatory levels by affecting gene expression and by their effects as phosphatase enzymes.
Lipin 1 is the lipin isoform that is most highly expressed in skeletal muscle. Recent work has demonstrated that rare mutations in the gene encoding lipin 1 in humans (LPIN1) lead to recurrent, episodic rhabdomyolysis that manifests mainly when these patients are children. In collaboration with Dr. Robert Bucelli, who has identified patients with LPIN1 mutations in the St. Louis area, we characterized a novel mutation in lipin 1 and teased apart the effects of several disease-causing mutations on the activities of the protein. While many mutations were complete loss of function, it was determined that some of the mutations caused a loss of enzymatic activity of lipin 1 protein without affecting its ability to regulate gene transcription. This suggests that defects in lipin’s lipid phosphatase activity leads to pathologic changes that explain the etiology of rhabdomyolysis in these patients.
To better understand this, Dr. George Schweitzer in the Finck group created novel mice with skeletal muscle-specific knockout of lipin 1. While outwardly normal, skeletal muscle of the knockout mice exhibited a chronic myopathy with ongoing muscle fiber necrosis and regeneration. These mice also exhibited accumulation of the lipid substrate of lipin 1, phosphatidic acid, in muscle. Additionally, lipin 1-deficient mice had abundant, yet abnormal mitochondria likely due to impaired autophagy. Phosphatidic acid suppresses autophagy by a variety of mechanisms, including by stimulating the activity of the mTOR kinase signaling cascade, which can be targeted by pharmacologic means.
While these mice do not completely phenocopy the episodic nature of patients with the human LPIN1 mutation, these data suggest that mice lacking lipin 1-mediated PAP activity in skeletal muscle may serve as a model for further exploration of the mechanisms by which lipin 1 deficiency leads to myocyte injury. We also hope to use these mice to test potential therapeutic or preventative approaches. Lastly, the lab is also interested in determining whether lipin 1 deactivation in other more common forms of muscular dystrophy may contribute to the progression of those diseases by similar mechanisms.
September 2019 – Jianjun Guan, PhD
The Polymers, Interfaces, and Regenerative Medicine lab led by Prof. Jianjun Guan at the Department of Mechanical Engineering and Materials Science is interested in biomimetic biomaterials synthesis and scaffold fabrication; bioinspired modification of biomaterials; injectable and highly flexible hydrogels; bioimageable polymers for MRI and EPR imaging and oxygen sensing; mathematical modeling of scaffold structural and mechanical properties; stem cell transplantation; and bone, skeletal muscle, skin, and cardiac regeneration.
One of the projects in Dr. Guan’s lab is to regenerate vasculature and skeletal muscle in ischemic limbs. Critical limb ischemia (CLI) is a severe peripheral artery disease with high rates of limb loss and mortality. It is featured by low blood perfusion, extensive tissue ischemia, and degenerated skeletal muscle. Quick vascularization to restore blood perfusion, and fast muscle regeneration to restore normal function, represent the optimal goals for CLI treatment. Currently there is no efficient treatment available, although stem cell therapy is one of the most promising strategies. However, current stem cell therapy experiences low efficacy largely due to inferior cell survival and paracrine effects under the extremely low oxygen condition of ischemic limbs. Dr. Guan’s lab is developing a new cell delivery system that continuously releases appropriate concentration of oxygen to simultaneously improve stem cell survival and paracrine effects, resulting in quick vascularization and muscle regeneration. Paracrine effects concurrently provide multiple growth factors critical for limb regeneration, which cannot be readily achieved by growth factor therapy. The team found that the oxygen-releasing cell delivery system can fully restore blood perfusion and muscle contractility in four weeks.
Figure 1. H&E staining of muscle sections from ischemic limbs 4 weeks after critical limb ischemia (CLI) surgery.
MSC: bone marrow derived mesenchymal stem cell; ORM: oxygen release microsphere.
November 2018 – Christine Pham, MD
Director – Division of Rheumatology
One of the focuses in the Pham lab is to develop novel approaches to deliver therapeutics that will halt or reverse joint inflammation and degeneration in preclinical models of rheumatoid arthritis and osteoarthritis, with the ultimate goal of translating these findings to the clinic. These projects represent a team-science, interdisciplinary approach to arthritis research, combining the Pham lab expertise in basic mechanisms underpinning these rheumatic conditions with innovative bioengineering advances in nanomedicine and regenerative medicine pioneered by outstanding collaborators in the Departments of Orthopaedics and Bioengineering. We collaborated with Drs. Linda Sandell, Farooq Rai, Farshid Guilak, and Sam Wickline (currently at University of South Florida) to deliver a peptide-siRNA nanocomplex targeting the NF-kB pathway to mitigate inflammation in murine models of rheumatoid arthritis and post-traumatic osteoarthritis. We have shown that peptide- NF-kB p65 siRNA nanocomplex suppresses experimental rheumatoid arthritis. We also leveraged the expertise and support of the Musculoskeletal Research Center, specifically the Structure and Strength Core and the Musculoskeletal Histology and Morphometry Core to conduct a murine model of controlled knee joint impact injury to test the hypothesis that delivery of peptide- NF-kB p65 siRNA nanocomplex in the immediate aftermath of joint injury will prevent cartilage degeneration and the eventual development of post-traumatic osteoarthritis. We showed that peptide-siRNA nanocomplex suppresses NF-kB activation (Figure 1) and mitigates several important early events post injury, including chondrocyte apoptosis, thus reducing the extent of cartilage injury and reactive synovitis. In addition to structural changes, we have now shown that treatment with peptide-siRNA nanocomplex is associated with improvement in pain sensitivity post injury. These findings may lead to the development of a first-in-class disease-modifying nanotherapeutic approach to prevent post-traumatic osteoarthritis. More recently we have also collaborated with Dr. Guilak and Drs. Yun-Rak Choi and Kelsey Collins (postdoctoral scholars in the Guilak lab) to test the ability of a tissue-engineered stem cell-based system with autoregulated cytokine antagonist delivery to mitigate inflammation in a robust murine model of rheumatoid arthritis. The system employs genome-engineered pre-differentiated iPSCs to deliver anti-cytokine therapeutics, the production of which is driven by endogenous levels of inflammatory cytokines. Our data suggest that this “SMART” cell-based delivery of IL-1 receptor antagonist suppresses inflammation, prevents bone erosions and mitigates pain induced by inflammatory arthritis. In addition to work in pre-clinical models of diseases, our lab is also actively involved in several translational projects. Our translational work is partially supported by the Washington University Rheumatic Diseases Research Resource-based Center (WU-RDRRC), a NIAMS-funded mechanism. WU-RDRRC’s mission is to promote cross-disciplinary collaborations and to stimulate the development of new initiatives that will advance the pace of discovery, with the goal of disseminating and implementing research findings into the practice of personalized medicine.
Figure 1. Mouse knees were loaded with 6 Newtons on day 0 and and left untreated or injected IA with 0.1 mg of peptide-p65 siRNA nanocompex immediately and at 48 h after impact injury; knees were harvested on day 5 for analysis. Mean fluorescent intensity (MFI) of phospho (P)-p65 per chondrocyte in p65 siRNA or scrambled (scram) siRNA nanocomplex-treated knees was measured in the boxed area just outside of the impact zone (demarcated by white lines) from z-stack confocal images. Values represent mean ± SEM. N = 4 mice per treatment group. Scale bars = 100 mm. COL2 (red), type II collagen; F, femur; M, meniscus. DAPI (blue) stains nuclei. **P < 0.01 (Yan et al, PNAS 2016; 113:E6199-E6208. ).