Sugar Coating For Osteoporotic Bone

Osteoporosis in which the bones become weak and brittle, is a leading global health challenge. It can also impair the function of bone implants which are normally made of titanium (Ti). As there is less bone than normal at the site of implantation, these implants can loosen easily and persistent inflammation often accompanies. The study conducted by Chinese scientists from the University of Macau and Nanjing University, in collaboration with National Dental Centre Singapore is published in the journal Advanced Functional Materials.

The scientists have invented a bioactive coating that can be chemically linked onto normal Ti surface. The coating is made from a chemically-modified glycan (a string of sugars) can sequentially turn on and off inflammation on bone implants.

In osteoporotic conditions, it instructs the host macrophages (immune cells) to release the molecules that can activate bone cells and promote healing; this is ‘good inflammation’. When the bone cells grow and function to an extent, they naturally secrete an enzyme- alkaline phosphatase, to cut the chemically-modified glycan from the Ti surface. The ‘sugar-coated bullets’ invented by scientists can specifically kill macrophages to turn off ‘bad inflammation’ for better healing and higher safety.

The lead contact and corresponding author of this paper, Prof Chunming Wang at the University of Macau said, "Interestingly, these macrophages to be killed in the latter part of this healing process, are exactly the guys who have made the major contribution to release pro-bone forming cytokines in the earlier stage. So, we described this design as a 'bridge-burning' strategy."

The main advantage of this coating is that it can maximize the power of the limited number of bone cells around the implants under osteoporosis.

Under pathologic conditions it is unrealistic to sharply increase the number or stimulate the function of bone cells around the implants to achieve better bone-implant integration.

The co-corresponding author, Prof Lei Dong at Nanjing University added, “Our method harnesses the inherent power of immune responses to enhance implanting efficacy, without using complicated methods that might bring about safety issues.”

This coating showed favorable performance in a rat osteoporosis model. The scientist anticipate next-stage research to be carried out in larger animals.

Source-Medindia