Angiogenesis: light shows blood vessels the way

Regenerative medicine aims to replace damage in the body with functional tissue and restore normal function. The first defense for large defects are implants made of hydrogels, designed to promote cell growth. They need their own blood supply, which is a problem when it comes to larger implants because you cannot regulate where and how the blood vessels grow - until now.

In this MEDICA-tradefair.com interview, Prof. Aránzazu del Campo explains how laser light and photoactive molecules can regulate the development of new blood vessels and reveals how this can benefit regenerative medicine.

Prof. del Campo, you study biomaterials for light-guided angiogenesis. What is that exactly?

Prof. Aránzazu del Campo: We aim to use laser light to regulate where and when blood vessels - and possibly down the road neurons - grow in implanted hydrogels. You need scaffolds to prompt cells to grow if you want to repair serious damage or injury to the body. Hydrogel implants are often used as scaffolding material. They provide a long-term replacement of the lost tissue and fill the defect area.

Endothelial cells are one of the first types of cells to grow into these scaffolds, which then form blood vessels. The implant and all cells cannot survive for long without blood supply.

How can your research benefit the field of regenerative medicine?

del Campo: We could speed up the regenerative process if we were able to control the location and direction of blood vessel growth. If there are no endothelial cells - and therefore no blood vessels - present, other cells will also have difficulties growing into the implants. There is no regeneration.

This could also facilitate more extensive regeneration as the blood vessels in these types of implants do not always grow the same way. Many organs also need blood vessels in certain places or in a certain pattern. We could guide the vessels to the right location and stimulate their growth.

How exactly does the process you are developing work?

del Campo: We have loaded implantable hydrogels with photoactive molecules that contain growth factors. Under normal conditions, these molecules lie dormant (latent) in the hydrogel. Once they are irradiated by light, they are activated and release the growth factors. They stimulate the endothelial cells to form new blood vessels in the irradiated areas. This allows us to control the location in the hydrogel where new blood vessels are meant to develop after implantation. That’s the amazing aspect of this process.

What materials do you use?

del Campo: We use both natural and synthetic hydrogels that have already been approved for medical applications. Given that we only add a very small number of photoactive molecules to them, they are essentially not considered new materials. We merely refine the material. This is helpful when it comes to approval for future medical applications down the road.

What are some possible applications of your procedure?

del Campo: The process could be used wherever you need to control the direction of growth. One example is the field of ophthalmology. When it comes to the eye, it is important to control where blood vessels grow and where they should not be growing. This does not just apply to blood vessels. Neurons also have a preferred direction of growth. That’s why this process could also be interesting in the field of neurosurgery, where it could support nerve growth and the joining of damaged nerves.

What are your next steps?

del Campo: We have shown proof of concept via in vitro studies and demonstrated that we can regulate angiogenesis with light. Animal testing has also been successful. Our next step is to test more effective photoactive molecules and, more specifically, study in vivo applications to show their benefits.