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Cellular and Molecular Bioengineering

Cellular and Molecular Bioengineering - Poster Session D

Poster I10 - Studying the impact of obese adipose tissues on cartilage - a pilot study

Friday, October 25, 2024

3:30 PM - 4:30 PM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

Matthew Murrison

Honors Bioengineering Student
University of Pittsburgh
Branchburg, New Jersey, United States

Co-Author(s)

SH

Sophie Hines

Graduate Student
Department of Bioengineering, University of Pittsburgh Swanson School of Engineering & Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, United States
Meagan Makarczyk

Graduate Student
Department of Bioengineering, University of Pittsburgh Swanson School of Engineering & Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine
Pittsburgh, Pennsylvania, United States

Primary Investigator(s)

HL

Hang Lin

Primary Investigator
Department of Bioengineering, University of Pittsburgh Swanson School of Engineering & Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, United States

Introduction: Osteoarthritis (OA) is a debilitating total joint disease that affects approximately 25% of adults in the United States. While direct causation is still unclear, known risk factors include age, trauma, genetics, and, notably, obesity. Obesity is classified as a systemic disease that causes global low-grade inflammation due to the secretion of proinflammatory adipokines from hypertrophic adipose tissue. Some proinflammatory adipokines are also seen in non-weight-bearing osteoarthritic joints, which suggests a biochemical correlation that must be further investigated to understand the true pathophysiology of the disease.

In this study, we differentiated hBMSCs (human Bone Mesenchymal Stem Cells) into adipose and cartilage tissues. We then induce adipocyte hypertrophy using sodium. Cartilage gels were finally exposed to conditional media from normal or obese adipose tissues to test the hypothesis that obese adipose tissues will induce cartilage degradation when compared to normal adipose tissues.

Materials and

Methods: Adipose tissue gels were generated by culturing passage 5 (P5) human Bone Mesenchymal Stem Cells (hBMSCs) within 15% methacrylated gelatin (GelMA) scaffolds, followed by photocrosslinking under UV light at 395 nm for 1 ½ minutes on each side. The gels were supplemented with an adipogenic differentiation medium comprising DMEM/F12, 10% FBS, 1% Antibiotic-Antimycotic, 0.1% IBMX, 0.1% Dexamethasone, and 0.1% ITS+. Initial differentiation was conducted over 28 days with media changes every 3 days. Subsequently, a subset of adipose gels was supplemented with sodium palmitate (SP) to induce obese-like changes in adipose tissue over 14 days. Cartilage gels were created using MSCs enclosed in GelMA. Conditional media from adipose gels in GM and adipose gels in GM+SP were individually added to cartilage gels for 48 hours. Tissues from (1) adipose gels in GM, (2) adipose gels in GM+SP, (3) Cartilage gels in conditional media from (1), and (4) Cartilage gels in conditional media from (2) were collected for RNA extraction using a Qiagen RNeasy Plus Universal Kit, intended for reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and histological analysis.

Results, Conclusions, and Discussions: Histological analysis revealed that adipose gels treated with SP exhibited increased lipid droplet diameter and quantity compared to regular adipose gels, indicating hypertrophy and hyperplasia. We also observed the higher expression of adipogenic markers such as PPARγ1 and PPARγ2, as well as baseline levels of inflammatory markers such as IL-6 (Interleukin 6) and TNF-α (Tumor necrosis factor-alpha) in SP-treated adipose tissues. Currently, we are culturing cartilage gels with conditional media from adipose gels treated by control or SP. We expect higher upregulation of articular cartilage degradation markers such as matrix metalloproteinase-13 (MMP13), a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS4), and ADAMTS5, and of proinflammatory cytokines, including interleukin-6 (IL-6) and IL-8 in obese adipose tissue-treated cartilage.

This study aimed to elucidate the biochemical relationship between obesity and osteoarthritis (OA) by investigating the effects of normal and obese adipose tissue on cartilage tissue. Our findings highlight the multifaceted impact of obesity on OA pathogenesis, driven primarily by biochemical factors.

Our findings highlight the importance of targeting adipose tissue inflammation in therapeutic strategies for OA, suggesting that interventions aimed at reducing adipokine secretion or blocking their effects on cartilage could mitigate the progression of OA in obese patients. Future methods will be to analyze the biomechanical involvement obesity has on OA. Mechanical loading could be applied to the two different cartilage groups to understand the impact increased mechanical stress has on the cytokine production of inflamed tissues. Creating a method to analyze both the biochemical and biomechanical aspects in conjunction will aid in understanding OA disease pathology and help to come up with a Disease Modifying Ostheo Arthritis Drug (DMOAD).

Acknowledgements (Optional):