06-01 beach sun vacation

[Image above] When vacationing outdoors, it’s important to remember sunscreen—repeated and severe sunburns can increase your risk of skin cancer later in life. Credit: Pixabay

With this past Memorial Day weekend kicking off the summer travel season, experts are expecting increased travel to outdoor destinations as people look to vacation while maintaining social distance.

Forgetting sunscreen may not seem that big of a deal, but it could have far-reaching consequences—studies show that repeated and severe sunburns can increase your risk of skin cancer later in life. In a worst-case scenario, you may develop melanoma, which is considered the deadliest form of skin cancer because it typically spreads to other areas of the body if left untreated.

For people who do develop melanoma, treatment commonly involves combining chemotherapy or radiotherapy with surgical removal of the affected tissue or organ.

“However, incomplete surgical resection usually causes recurrence, and the refractory wounds left by the surgery are hard to self-heal, even prone to secondary injury due to infection. Consequently, there are pressing needs to develop multifunctional biomaterials with simultaneous tumor-killing and skin tissue regeneration capability for desirable therapeutic efficacy,” researchers write in a recent open-access paper.

The researchers come from several institutions in China, along with colleagues from Sabancı University in Turkey and Queensland University of Technology in Australia. In their paper, they explain that an emerging treatment called photothermal therapy—which uses electromagnetic radiation to induce localized heating within tissue to kill cancer cells—has received much attention due to its “high selectivity, minimal invasiveness, and no systemic effect compared with traditional chemotherapy/radiotherapy.”

In photothermal therapy, molecules called photothermal agents are placed in the tumor tissue, and these molecules are heated by electromagnetic radiation to kill cancer cells. Development of new photothermal agents is an ongoing area of research, yet to date the photothermal agents investigated for melanoma treatment have suffered drawbacks such as limited bioactivity and acute inflammation, limiting further clinical applications of this treatment.

The researchers note that a photothermal agent with good biocompatibility and high efficiency of photothermal conversion in addition to a wound repair effect would be ideal for melanoma treatment. To achieve all of these properties, the researchers suggest manganese-doped silicate bioceramics may be a good starting point for exploration.

“Silicate bioceramics offer a great prospect in the field of tissue engineering including skin, bone, and cartilage regeneration,” they write. “Moreover, the manganese (Mn) element plays a vital role in extracellular matrix synthesis and shows great potential in bone tissue regeneration … [and] could endow silicate bioceramics with excellent photothermal performance. Consequently, it is reasonable to speculate that Mn-doped silicate biomaterials can possess both tumor-killing and wound healing capabilities, which offer high potential for melanoma therapy and wound healing.”

However, applying bioceramic powders directly for wound healing is difficult due to high pH at wound sites, nonuniform distribution, and potential cytotoxicity caused by excessive metal ions, among other challenges. Fortunately, “To solve these problems, an appropriate wound dressing biomaterial could be used to load the bioceramic powders.”

In their study, the researchers investigated loading manganese-doped calcium silicate nanowires into sodium alginate hydrogel, a material widely used in wound dressing and other tissue engineering fields. They used this bifunctional composite bioceramic hydrogel (which they termed MCSA) for postoperative treatment of malignant melanoma in mice.

In vivo photothermal therapy using the laser-irradiated bifunctional composite bioceramic hydrogels significantly inhibited skin melanoma tumor growth, and the wounds gradually healed without obvious tumor recurrence within 14 days. Of the tumor cells that did remain, most were apoptotic, i.e., undergoing cell death.

“According to the results above, the conjecture could be confirmed that tumor cells were eradicated by the photothermal therapy in the early treatment stage, and then skin defects induced by skin tumors were stimulated and repaired with the MCSA hydrogels,” the researchers write.

Thus, “The results showed that the developed bifunctional MCSA hydrogels would be an excellent candidate for integrative melanoma photothermal therapy and wound healing processes,” they conclude.

The open-access paper, published in Research, is “Manganese-doped calcium silicate nanowire composite hydrogels for melanoma treatment and wound healing” (DOI: 10.34133/2021/9780943).