Longevity Briefs: How To Repair A Broken Heart

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

Why is this research important: Collectively, no disease causes as much death around the world as cardiovascular diseases disease (CVD). The most common CVD is coronary artery disease, in which cholesterol is deposited in the arteries supplying the heart muscle. This makes them narrower, reducing blood supply to the heart or cutting it off entirely if a blood clot forms, resulting in a heart attack. This is ultimately a disease of ageing that everyone will experience if they live long enough.

Even if blood flow can be restored, heart muscle that was starved of blood remains damaged and scarred, weakening and stiffening the heart and increasing the risk of further problems. Unfortunately, the heart is very bad at regenerating itself in comparison to most other organs, meaning that any damage is essentially permanent. Because of this, scientists have been looking for ways of regenerating the heart by introducing new cardiac muscle cells, but so far haven’t been very successful.

What did the researchers do: In this article, researchers give us an overview of the past and future attempts to engineer new cardiac tissue. Can it be done, why have previous attempts failed, and what’s the winning strategy likely to be?

Key takeaway(s) from this research:

• Approaches that work in other tissues don’t work in the heart due to the complexity of the heart tissue.
• Scientists aren’t sure what cells types are best for replicating the properties of heart tissue.
• Current approaches focus on placing heart cells in a ‘scaffold’ that mimics the protein scaffolding of the heart. This can be produced artificially or by removing cells from an existing heart.
• Despite difficulties, cardiac tissue engineering is a field with a lot of potential to improve health and save many lives.

In their first attempts at regenerating the heart, scientists hoped that simply introducing new, self-renewing heart cells into damaged heart tissue would be enough to repair it, similar to the way in which bone marrow transplants work. Unfortunately, this turned out to be more challenging than expected. Heart tissue is made up of different cell types with a specific arrangement. New heart cells need to properly integrate into existing tissue in a way that allows electrical signals to pass through the heart muscle unimpeded. Different cell types (such as regular muscle cells and stem cells) have been tested in an attempt to replicate the properties of heart tissue, but all have their own limitations and drawbacks.

The focus is now on cardiac tissue engineering. This means that different cell types are placed in a ‘scaffold’ that mimics the protein scaffolding within the heart, then supplied with growth factors in order to create heart tissue with the desired electrical and mechanical properties. However, researchers are still figuring out what the best way to do this may be. One promising approach is to remove all the cells from an animal heart, leaving the scaffolding intact for repopulation with the patient’s cells.

The authors also suggest that the mechanical properties of the materials used in cardiac tissue engineering could be the key to success. That’s because the way heart cells grow, function and communicate with each other has been found to be influenced by physical forces from their environment, such as tissue stiffness and blood pressure.

Despite decades of research, the only real way of ‘repairing’ a damaged human heart remains to replace it with another human heart. However, hope is far from lost, as there is still plenty of room for innovation when it comes to cardiac tissue engineering.