Nanomedicine Chronicles: Could Injectable Sponges Deliver Drugs to Cells?
Sponges, though starring as main characters in cartoon shows like Spongebob Squarepants, have been denied their fair share of spotlight in the real world for quite some time because of their lack of differentiated tissues and simple lives. However, it turns out they are not as mundane as basic Biology portrays them to be. Sponges might have a role to play in things other than filtering the oceans, serving as dish-washing wipes and safety packaging material – important things, like nanomedicine.
If you’ve ever had the opportunity to visit museum gift shops, you might have seen dinosaur egg sponges. They’re little pellets that inflate into soft dino-shapes upon contact with water. Bioengineers at Harvard and Caltech, USA designed a new class of gel-based sponges that can be molded in any required shape or size, absorb drugs or soak up stem cells, shrink down and be injected into the body through a syringe, where they inflate to their original size and allow their contents to leak out. You could imagine them as something similar to the dino sponges – only they’ll be inside the body.
Minisponges saturated with medicine could work as minimally invasive healing kits. Left: Upon hydration a fully collapsed square-shaped cryogel rapidly regains its original memorized shape, size, and volume. Right: Photos show a cryogel being placed inside a 1-mL syringe, and the recovery of a square gel after injection through a normal 16-gauge needle. Courtesy of Sidi Bencherif
These sponges are basically composed of alginate, a gel made from algae, through the process called cryogelation, forming patterns of ice crystals throughout the alginate as it is frozen. As the crystals melt and the water flows away, the gel is left with a network of pores, prevents the alginate from being brittle and keeping it soft and spongy. The sponges have large pores that can hold cells, allow passage to liquids, large molecules like proteins and small-molecule drugs. When the alginate safely degrades in the body over time, the drugs, cells or proteins it carried within the pores easily pass out.
David J. Mooney, a bioengineering professor at Harvard’s School of Engineering and Applied Sciences said, “At sites of injury or infection, the sponges could be promising new tissue scaffolds. They could transplant stem cells, bulk up tissue that’s been lost or degenerated, or even transplant immune cells. Since they can be built in any shape, the team made hearts, stars and squares – they could theoretically be used for any size or shape area in the body.”
“Some lab tests were carried out showing that cells that were delivered with the sponges worked better than transplanted cells that were injected in a standard way, without sponges. The next step is focused on refining the sponges so they’d release their contents in precisely timed ways,” Mooney said.
The research published in the Proceedings of the National Academy of Sciences gives insight into new frontiers in nanomedicine that pave the path for further research that could hopefully lead to better management of patients.
Source: Harvard School of Engineering and Applied Sciences
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