Sounds weird, right? Super exciting stuff here. So, a project led by Richard Cheng, working at the Institute of Biomaterials and Biomedical Engineering (IBBME) department at the University of Toronto, has created a machine that basically “prints a form of skin”. Cheng has been working under the supervision of Associate Professor Axel Guenther in the mechanical and industrial engineering department during the development of this skin printing machine.
The first version of the machine was announced in 2018. However, this is now more newsworthy because these engineers have also released a study showing that the skin helps burn wounds heal better. Before the original release of this skin printing machine, it was only theorized, but now, they claim that this machine works, perhaps even better than skin grafting. Guenther claims, “Previously, we proved that we could deposit cells onto a burn, but there wasn’t any proof that there were any wound-healing benefits – now we’ve demonstrated that”. This is about the tenth, or so, version of this machine to be developed. So, let’s dig a little deeper into this.
Firstly, we should ask why we would need a gun or machine that prints a form of skin?
Well, it could be helpful for a few reasons:
1. Most methods of skin grafting involve harvesting skin from the individual that suffered the burn. In other words, we take your skin to help heal your burn injury. These grafts are referred to as ‘autografts,’ and the sites of skin harvest are ‘donor sites’. However, the grafting process causes several issues with patients.
Donor sites are painful, and some burn patients even complain about the pain of these sites hurting MORE than their actual burns, and we all know burns are an excruciating wound. Therefore, using a device like this one could potentially reduce the amount of pain a patient experiences.
2. When burn surgeons harvest skin, it creates a second wound. For example, if 10% of your body surface area (TBSA) was burnt and they have to take 10% of your skin to graft, you now have a 20% TBSA wound. Now, your chances for infection have doubled, and as mentioned above, the additional pain is substantial. So, a device like this is not only ameliorating pain inflicted but could potentially also reduce the rates of infection.
Now, let’s look at how the device itself functions:
The device utilizes several different materials and combines them, and then it spreads these materials across the burnt tissue (or wound bed) that has been previously excised. Excision is the process of removing dead tissue from the wound bed. This removal of dead tissue allows the new tissue, such as a graft, to adhere to the wound bed and facilitate healing.
This device utilizes an exciting type of cell called Mesenchymal Stromal Cells (MSCs). Basically, it fabricates sheets of them in combination with some other organic properties to help the “skin sheet” become adherent to the wound bed. MSCs are isolated from bone marrow or other tissue sources and have properties similar to stem cells, though they are not totipotent. This means they are not capable of differentiating into any tissue, but MSCs have the potential to become tissue that would be helpful in the healing of wounds, hence why they are being used for this type of graft printing machine.
Though these cells can become a variety of different cells (see graphic below), they are most notable and researched for their ability to differentiate into skin cells, bone cells, and cartilage cells. In tissue with an acute inflammatory response, white blood cells will produce a growth factor that will trigger local MSCs to begin their differentiation process. So, it is theorized that these cells could help multiple types of wounds heal. It should be noted as well that there is currently no human application for using MSCs right now as all experiments remain in clinical trials at this time. However, just like in this study, it seems to be a promising avenue to continue down as far as research is concerned.
There have been many studies on MSCs and what they are and are not capable of doing. One property they do seem to have is the ability to reduce inflammation when introduced into a wound. They do this by blocking several of the inflammatory factors that naturally occur inside of an injury. For burns, reducing inflammation is incredibly important for wound healing. The more swollen a wound is, the less blood can flow to it and without good oxygen and nutrient exchange at the cellular level, recovery becomes even more difficult.
After testing on porcine, the scientists concluded that the device not only deposited “skin sheets” on the wounds effectively and reliably, the sheets did not “shear”, which means they did not shift or move; they adhered well to the wound bed itself. But more significantly, the scientists claimed that these wounds also healed “extremely well” with a reduction in scarring (which could potentially mean less contracture) and a decrease in inflammation, which we previously discussed with the MSCs.
So, what happens next? What are the next steps? Well, at this point, either more animal trials need to be done, or an application for clinical trials on humans needs to be completed and approved. This process can be a long one, as the FDA has a wide variety of compliance requirements for human testing, as they should.
I think this work is promising and would love to see it enter the stages of human testing within the next few years.
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