R. Porter (Little Rock, US)

University of Arkansas for Medical Sciences Center for Musculoskeletal Disease
Ryan Porter is an Assistant Professor in the College of Medicine at the University of Arkansas for Medical Sciences (UAMS). He earned degrees in Chemical Engineering from the University of Kentucky (BSc) and Virginia Tech (MSc; PhD); with a graduate program emphasis in Biomedical Engineering. Ryan received his postdoctoral training at Harvard Medical School with Prof. Christopher Evans. In 2012; Ryan became research faculty in the Department of Orthopaedic Surgery at Beth Israel Deaconess Medical Center (BIDMC). He moved to UAMS in late 2017; joining the Departments of Internal Medicine and Orthopaedic Surgery. Ryan’s laboratory generally focuses on developing cell or molecular therapies to direct skeletal tissue repair or prevent tissue degeneration (e.g.; osteoarthritis). Currently his group is pursuing two active areas of research: one focused on improving the intra-articular delivery of molecular therapeutics within synovial joints; the other on overcoming key bottlenecks to simulating chondrogenesis in vivo by culture-expanded chondroprogenitor cells. At present; these projects use rat and rabbit models of joint injury to help answer specific questions. Ryan is interested in establishing new collaborations that address the above challenges in skeletal regenerative medicine. His group brings to the table expertise in the progenitor cell biology and rodent models of bone/cartilage repair and intra-articular therapy.

Presenter Of 1 Presentation

Podium Presentation Animal Models

12.1.3 - A Chondrogenesis Reporter Rat for Evaluating Strategies to Stimulate Cartilage Repair

Presentation Topic
Animal Models
Date
13.04.2022
Lecture Time
16:48 - 16:57
Room
Bellevue
Session Name
Session Type
Free Papers
Disclosure
No Significant Commercial Relationship

Abstract

Purpose

To support the preclinical development of novel treatments for cartilage injury, we generated a transgenic rat strain that can noninvasively report chondrogenesis for correlation with endpoint measures of tissue repair.

Methods and Materials

All animal studies were pre-approved by the local institutional ethics committee. A transgene was constructed in which the dual expression of bioluminescent (firefly luciferase) and fluorescent (mCherry) reporters is controlled by regulatory sequences from rat Col2a1. A transgenic line was established on a Lewis background and characterized by serial bioluminescence imaging and ex vivo measurement of reporter levels. The sensitivity and specificity of the strain were assessed using an osteochondral defect model in 6 month old or 2 year old rats. To stimulate healing, some defects were treated with rat bone marrow stromal cell aggregates.

Results

Bioluminescence imaging of the strain revealed substantive signal from cartilaginous regions, including the appendicular synovial joints, spine, sternum, nose, and pinnae. Bioluminescent radiance declined with postnatal development yet remained detectable in aged animals. Explant imaging, immunohistochemistry, and gene expression confirmed that both firefly luciferase and mCherry expression were localized to cartilage. Implantation of wild type bone marrow stromal cells into osteochondral defects made in young adult reporter rats led to a temporal elevation of intra-articular reporter activity concurrent with cartilaginous tissue repair (Figure 1). For aged rats, higher variability in bioluminescence signal was associated with generally poor repair of the cartilage phase with some restoration of the osseous phase. While mCherry-positive cells were detected in aged repair tissue, senescence associated β-galactosidase and p16INK4A immunostaining indicated the presence of abundant senescent cells (Figure 2). Ongoing studies are determining the influence of senolytic drug delivery on reporter activity and cartilage formation.

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Conclusion

The reporter strain can serve as an initial preclinical model for testing strategies to stimulate chondrogenesis within articular cartilage defects.

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Moderator Of 1 Session

Bellevue Special Session
Session Type
Special Session
Date
13.04.2022
Time
10:45 - 11:45
Room
Bellevue
Session Description
Worldwide experts share the current information on cartilage morphogenesis, signaling, inflammation and immunity, and epigenetic regulation of disease.
Session Learning Objective
  1. Participants will be provided novel insights into the processes of morphogenetic development involved in cartilage signaling and homeostasis and of the levels of regulation of tissue inflammation and immunity, including at the epigenetic level.
CME Evaluation (becomes available 5 minutes after the end of the session)