A Polymer That Helps Body Accept Implants Better
By Express News Service | Published: 09th February 2015 06:00 AM |
BENGALURU: Drug delivery devices like implants offer several advantages over pills or injections, but often result in immune responses that hinder their performance.
Now, a group of researchers, led by Professor Bikramjit Basu of the Materials Research Centre and Bio-Engineering Programme, and Professor Giridhar Madras of the Department of Chemical Engineering, Indian Institute of Science (IISc), have developed a biodegradable polymer that acts as an anti-inflammatory agent and allows better acceptance of biomedical implants in the human body.
The study was published in the journal ‘Biomacromolecules’ recently.
Implantable devices facilitate drug delivery at specific regions of the body where they are required.
This local delivery provides an advantage of using lower doses of drug and thereby reducing the potential side effects.
The novel biodegradable Salicylic Acid-based Polyester (SAP) is designed to slowly deliver salicylic acid (a Non-Steroidal Anti-Inflammatory Drug-NSAID) for a prolonged period of time.
“Other salicylic acid-releasing polymers belong to a class of poly (anhydride) esters and are linear or have salicylic acid conjugated to a linear chain. Anhydride linkages in these polymers are very labile and therefore unstable,” said primary author and PhD student Yashoda Chandorkar of Materials Research Centre.
“The SAP synthesised by us is cross-linked. Ester linkages are known to be stable compared to anhydride linkages. This difference in the chemical structure is the main reason for the sustained release that is possible over a prolonged period of time with our polymer,” Chandorkar said.
Implantation of SAP in mice reduced the Foreign Body Response (FPR) and formation of an undesirable coating around it. This coating/fibrous capsule prevents effective communication between the implant and body. “Commonly used biodegradable polymers such as poly (lactic acid-co-glycolic acid-PLGA) have noxious degradation products, which are undesirable for an ideal system,” Chandorkar said.
A comparison following implantation in mice for 2, 4, and 16 weeks, showed that fibrous capsule surrounding the PLGA implant was denser. However, the SAP implant was surrounded by normal tissue-like structure. Moreover, 96 per cent of PLGA versus 8 per cent SAP degraded by 16 weeks. This slow degradation results in sustained release of salicylic acid, she said.