Features | Partner Sites | Information | LinkXpress
Sign In
JIB
GLOBETECH PUBLISHING
GLOBETECH PUBLISHING

Shape Memory Polymer Designed to Help Reconstruct Faces

By BiotechDaily International staff writers
Posted on 27 Aug 2014
Image: A material that changes shape when heated could be used to make custom implants. The white bar is 1-cm-long (Photo courtesy of Melissa Grunlan, Texas A&M).
Image: A material that changes shape when heated could be used to make custom implants. The white bar is 1-cm-long (Photo courtesy of Melissa Grunlan, Texas A&M).
Researchers have developed a “self-fitting” material that expands with warm salt water to effectively fill bone defects, and also acts as a scaffold for new bone growth.

Birth defects, such as cleft palates, injuries, or surgery to remove a tumor can create gaps in bone that are too large to heal naturally. Furthermore, when they occur in the head, face, or jaw, these bone defects can dramatically alter an individual’s appearance.

The researchers described their approach at the 248th National Meeting & Exposition of the American Chemical Society (ACS), the world’s largest scientific society, on August 13, 2014, held in San Francisco (CA, USA). Currently, the most common way to fill bone defects in the face, head, or jaw (the cranio-maxillofacial area) is autografting: a process in which surgeons harvest bone from somewhere else in the body, such as the hip bone, and then try to shape it to fit the bone defect. “The problem is that the autograft is a rigid material that is very difficult to shape into these irregular defects,” said Melissa Grunlan, PhD, leader of the study.

Moreover, harvesting bone for the autograft can itself create complications at the place where the bone was taken. Another strategy is to use bone putty or cement to fill gaps. However, these materials are not ideal. They become very brittle when they harden, and they do not have pores, or small holes, that permit new bone cells to move in and reconstruct the damaged tissue.

To develop a better material, Dr. Grunlan and her colleagues from Texas A&M University (College Station, USA) constructed a shape-memory polymer (SMP) that molds itself precisely to the shape of the bone defect without being brittle. It also supports the growth of new bone tissue.

SMPs are materials whose geometry changes in response to heat. The investigators made a porous SMP foam by linking together molecules of poly(ε-caprolactone), an elastic, biodegradable substance that is already used in some medical implants. The resulting material resembled a stiff sponge, with many interconnected pores to allow bone cells to migrate in and grow. Upon heating to 60 °C, the SMP becomes very soft and pliable. Therefore, during surgery to repair a bone defect, a surgeon could warm the SMP to that temperature and fill in the defect with the softened substance. Then, as the SMP is cooled to body temperature, it would resume its former stiff texture and “lock” into place.

The researchers also coated the SMPs with polydopamine, a sticky substance that helps lock the polymer into position by inducing formation of a mineral that is found in bone. It may also help osteoblasts, the cells that generate bone, to stick and spread throughout the polymer. The SMP is biodegradable, so that eventually the scaffold will disappear, leaving only new bone tissue behind.

To evaluate whether the SMP scaffold could support bone cell growth, the researchers seeded the polymer with human osteoblasts. After three days, the polydopamine-coated SMPs had grown about five times more osteoblasts than those without a coating. Furthermore, the osteoblasts produced more of the two proteins, runX2 and osteopontin, which are critical for new bone formation.

Dr. Grunlan reported that the next phase of the research will be to evaluate the SMP’s ability to heal cranio-maxillofacial bone defects in animals. “The work we’ve done in vitro is very encouraging,” she says. “Now we’d like to move this into preclinical, and hopefully, clinical studies.”

Related Links:
Texas A&M University


comments powered by Disqus

Channels

Genomics/Proteomics

view channel
Image: Differences in the structure of a small lung artery (top row) and heart cross section (lower row) of rodents without disease (far left column); with pulmonary hypertension (middle) and a diseased rodent treated with the HDL peptide (right). Note the much narrowed lung artery, and thick walls and larger chamber of the heart in the diseased animal and improvements with 4F peptide treatment (Photo courtesy of UCLA - University of California, Los Angeles).

Apolipoprotein A-1 Mimetic Peptide Reverses Pulmonary Hypertension in Rodent Models

A small peptide that mimics the activity of apolipoprotein A-1 (apo A-1), the main protein component of the high density lipoproteins (HDL), counteracted the effects of oxidized lipids and alleviated symptoms... Read more

Drug Discovery

view channel
Image: The five stages of biofilm development: (1) Initial attachment, (2) Irreversible attachment, (3) Maturation I, (4) Maturation II, and (5) Dispersion. Each stage of development in the diagram is paired with a photomicrograph of a developing P. aeruginosa biofilm. All photomicrographs are shown to same scale (Photo courtesy of Wikimedia Commons).

Ionic Liquids Disperse Bacterial Biofilms and Increase Antibiotic Susceptibility

The ionic liquid choline-geranate was shown to effectively eliminate the protective biofilm generated by bacteria such as Salmonella enterica and Pseudomonas aeruginosa and to significantly increase the... Read more

Therapeutics

view channel
Image: Hair follicle (blue) being attacked by T cells (green) (Photo courtesy of Christiano Lab/Columbia University Medical Center).

Hair Restoration Method Clones Patients’ Cells to Grow New Hair Follicles

Researchers have developed of a new hair restoration approach that uses a patient’s cells to grow new hair follicles. In addition, the [US] Food and Drugs Administration (FDA) recently approved a new drug... Read more

Business

view channel

Partnership Established to Decode Bowel Disease

23andMe (Mountain View, CA,USA), a personal genetics company, is collaborating with Pfizer, Inc. (New York, NY, USA), in which the companies will seek to enroll 10,000 people with inflammatory bowel disease (IBD) in a research project designed to explore the genetic factors associated with the onset, progression, severity,... Read more
 
Copyright © 2000-2014 Globetech Media. All rights reserved.