A barrier to successful transplantation of lab-grown organs and tissue is the inability to generate a viable network of blood vessels that integrates the new tissue into the patient. Now, a new way of growing blood vessels that uses patient-derived 3-D scaffolds – as opposed to artificial ones – could meet this need and deliver a significant boost to regenerative medicine.

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The researchers found that the lab-generated blood vessels (in green) were able to make new connections with sprouts protruding from the rat aorta tissue (in red). Image credit: Tiago Fortunato/University of Bath

Researchers from the University of Bath and the Bristol Heart Institute, both in the United Kingdom, describe their new technique for growing 3-D blood vessels in the journal Scientific Reports.

They suggest because their method of growing blood vessels in a 3-D scaffold uses cells from the patient, it reduces the risk of transplant rejection.

The idea of regenerative medicine is to replace damaged organs and tissues in patients with new ones. Ideally, these should be generated using material derived from the patient, so as to reduce the risk of rejection by the immune system.

An ideal application of such tissue engineering is heart failure, where the heart cannot pump enough blood around the body because the heart muscle has become weak or stiff. In theory, new heart muscle engineered in the lab could be transplanted to replace the worn out tissue in the patient.

However, in practice, regenerative medicine is held back because of problems with generating a blood supply to the new tissue.

Dr. Giordano Pula, research team leader and lecturer in pharmacology at the University of Bath, explains:

“A major challenge in tissue engineering and regenerative medicine is providing the new tissue with a network of blood vessels, and linking this to the patient’s existing blood supply; this is vital for the tissue’s survival and integration with adjacent tissues.”

If the method is proven to be successful in further studies of its potential applications, it could help improve the lives of the many people who are struggling to live with heart failure, says Professor Peter Weissberg, Medical Director of the British Heart Foundation, one of the study’s sponsors.

Fast facts about heart failure
  • About 5.1 million people in the United States have heart failure
  • One in 9 Americans who died in 2009 had heart failure
  • Risk factors include: smoking, eating high-fat foods, lack of exercise, and obesity.

Learn more about heart failure

Previous attempts to generate a 3-D network of blood vessels using human cells and synthetic scaffolds have not been very successful.

The new method relies on two materials: human platelet lysate gel and endothelial progenitor cells (EPCs) – a type of cell that helps maintain blood vessel walls.

Both the gel and the EPCs can be isolated from the patient’s blood. In their study, the researchers show how these can generate a network of small blood vessels.

They compared the new technique’s ability to grow new blood vessels inside the aorta tissue of rats against other methods that use collagen or fibrin gels.

The results show that over a 3-day period, the EPCs had established a new network of blood vessels within the human platelet lysate gel. This contrasted with “negligible formation of an interconnected capillary network within collagen I or fibrin gels.”

Co-author Dr. Paul De Bank, senior lecturer in pharmaceutics at the University of Bath, says that because the human platelet lysate gel contains a number of different growth factors, this stimulates existing blood vessels to infiltrate the gel and form new connections with the new vessels. He adds:

“Combining tissue-specific cells with this EPC-containing gel offers the potential for the formation of fully vascularised, functional tissues or organs, which integrate seamlessly with the patient.”

The researchers note that another advantage of their method is that because the gel comes from human platelets, it should be safer than gel derived from animal products.

This discovery has the potential to accelerate the development of regenerative medicine applications.”

Dr. Paul De Bank

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