Effect of human adipose stem cell-derived mitochondrial transplantation on the activity of chronically injured anterior cruciate ligament cells

Listen to Simon and Amy discuss the paper 'Effect of human adipose stem cell-derived mitochondrial transplantation on the activity of chronically injured anterior cruciate ligament cells' published in the September 2025 issue of Bone & Joint Research.

Click here to read the paper.

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Transcript

[00:00:00] Welcome back to another episode of AI Talks with Bone & Joint from the publishers of Bone & Joint Research. Today we're discussing the paper 'Effect of human adipose stem cell-derived mitochondrial transplantation on the activity of chronically injured anterior cruciate ligament cells', published in September 2025 by HL Lo and colleagues. I'm Simon and I'm here with my co-host Amy.

Hello Simon. This study is thoroughly intriguing as it examines the effect of mitochondrial transplantation derived from human adipose stem cells on ACL cells that have been chronically injured.

Let's start with the broader view. ACL injuries are among the most common in sports, particularly in activities involving sudden stops or changes in direction. These injuries can substantially affect one's ability to return to high levels of physical activity.

Traditionally, the optimal time for reconstructive surgery was believed to be around four to six weeks post-injury. This study investigates how the surgery timing impacts ACL [00:01:00] cell activity and their healing potential.

The researchers concentrated on two main objectives. Firstly, to investigate how the time from injury to surgery affects ACL cell activity and secondly, to evaluate the effectiveness of mitochondrial transplantation in enhancing the activity of these cells.

They carried out several detailed experiments using rabbit models to simulate ACL injuries. They harvested tissue samples from the ACLs at different stages post-injury, two weeks, four weeks, and eight weeks. They examined cell proliferation, migration capabilities, collagen synthesis, and gene expressions, including vascular endothelial growth factor VEGF, and transforming growth factor beta TGFβ.

The results were quite enlightening. The highest ACL cell activity was noted at four weeks post-injury. By eight weeks there was a marked decline in cell viability, migration capabilities, and collagen synthesis. This really highlights the importance of the timing for reconstructive surgery.

Indeed [00:02:00] Simon. What's especially exciting is that when they transplanted mitochondria derived from human adipose stem cells into these ACL cells, they observed significant improvements. The treated cells at eight weeks post-injury showed enhanced viability, migration, and collagen synthesis nearly matching the activity levels seen in four-week injured cells.

Yes, and the mitochondrial transplantation also resulted in a significant upregulation in VEGF gene expression, which is essential for promoting angiogenesis and tissue healing.

In addition to their in vitro studies, the researchers also conducted an in vivo study using a rabbit ACL partial tear model. They discovered that the transplanted mitochondria remained within the injured ACL tissue and significantly enhanced collagen synthesis. This has substantial implications for treating partial ACL tears, potentially delaying progression to complete tears.

Indeed, Amy, it's fascinating to consider the potential this holds for enhancing graft maturation and overall healing in [00:03:00] ACL reconstruction, particularly in cases where surgery might be postponed beyond that optimal four to six week window.

To summarize the study underscores two critical points, the vital importance of timing for ACL reconstruction, ideally around four to six weeks post-injury and the promising role of mitochondrial transplantation in improving the healing of chronically injured ACL cells. It's a captivating field of research that could pave the way for new biological treatments to improve outcomes for patients with ACL injuries.

That's all for today's episode of AI Talks with Bone & Joint. Thanks for joining us and stay tuned for more insights into cutting edge orthopaedic research. Thanks Simon and thank you listeners for tuning in. We'll see you next time.