Most human tissues are not designed to be regenerative in function. Therefore, when a body part, e.g., a limb, is amputated for any cause, it cannot be regrown. Although prosthetic and bionic technologists have built artificial limbs for the replacement of amputated ones, these artificial limbs cannot function as the natural ones: they cannot respond completely to the touch, pain, and pressure, or feel the warmth of the sun.
Amputee
This fact made the researchers in regenerative and developmental biology and biomedical engineering, go into research to find a way to bridge this gap. They were able to come up with a novel treatment that can induce the regeneration of a fully functional touch-sensational limb in frogs.
The study
The researchers went back into the early stage of the development of the human body. They figured out that the best way to invoke this regenerative characteristic of cells is to try to induce the activities of the cell during the early stage of development, at the site of an injury.
One major setback they encountered was how to cause the tissues around an injured site to be regenerative in function, instead of forming scars, because scar formation around an injured area changes the cellular environment in consideration, hindering regeneration mechanisms. They found that the amniotic sac, during embryonic development, enhances regeneration. So, they drew a hypothesis that creating a similar environment around injured areas of the body might produce the same regenerative effect.
They carried out the study using several amputated African clawed frogs (which like humans, do not exhibit regenerative properties). They developed a device – a wearable one – made of silk hydrogel (which would enhance regeneration and stop the signals for scar formation at the site of an injury), and filled it with a mixture of five drugs that stimulates normal tissue growth in animals. They divided these amphibians into three groups: to the first group, they wore the device on the cut leg, together with the drug; to the second group, they gave the device but not the drug; and to the third group, they gave neither device nor drug. The researchers were astonished by the results after 24 hours of using this device and drugs on the groups of frogs.
They found out that after 18 months, the first group of frogs, I.e., those that were given both device and drugs, were able to grow back their lost legs with nerves, blood vessels, and bones intact. They tested the regenerated legs for response to touch, pressure, and other sensations, and it was positive. The second group (those that were given device only) had poor limb regrowth, and no response to sensations, while the third group (those given neither drugs nor device), experienced no regrowth at all.
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However, they discovered also that the legs of the first group of frogs were not perfectly regrown, because they noticed that the bones sometimes fractured. This made them conclude that something was missing from the treatment. They are currently working to find out the missing element. Once discovered, they would include it in the treatment to make the whole process fully effective.
Clinical Significance
With this great discovery, doctors can finally restore not just a lost limb to their patients, but also the feeling of sensations to them. Patients who have had to lose a body part due to traumas resulting from car accidents, or complications from diseases such as diabetes, will be able to recover these body parts.
The knowledge from this discovery is also a stepping stone to uncovering regenerative mechanisms for heart tissues that experience heart attacks, and brain tissues that experience strokes – this can promote survival from such occurrences, and reduce the number of deaths arising from them.
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Conclusion
Although this novel treatment has not been clinically tested on humans yet, there is a high chance that it would produce the same effect as with frogs. If this turns out to be so, then people would not have to be in grief anymore due to the loss of a body part, since this finding has uncovered a way around it.
References
Murugan, N. J., Vigran, H. J., Miller, K. A., Golding, A., … & Levin, M. (2022). Acute multidrug delivery via a wearable bioreactor facilitates long-term limb regeneration and functional recovery in adult Xenopus laevis. Science Advances, 8(4). DOI: 10.1126/sciadv.abj2164. Retrieved from https://www.science.org/doi/10.1126/sciadv.abj2164
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