Michael Barbella, Managing Editor08.14.15
New medical device materials can come from the most unlikely of places: the ocean (Northern clingfish, sea snails, squid, barnacles and mussels, etc.), the insect world (spiders) and the reptile kingdom (geckos). They also can evolve from common substances like wood (which can mimic bone when subjected to various processes), glass (an excellent conduit of nervous system synergy), ceramics (a close match for natural teeth), and, oddly enough, foam.
Indeed, the material used most often to provide bodily comfort and protection is surprising researchers with its potential medical device bracing and pressure relieving applications. A new, high-performing auxetic version of foam developed by a Florida State University engineering professor for the U.S. Department of Veterans Affairs works counter-intuitively to the traditional material by becoming thicker rather than thinner when stretched. The innovation was part of the VA Innovation Initiative project, created to address the shortcomings of current prosthetic socket systems.
“We know what is not working with current products and technology, and what it is going to take to make it better,” Changchun “Chad” Zeng, Ph.D., told ScienceDaily. “For example, the socks that amputees currently use to attach prosthetic devices do not adjust to limb shape and volume, creating lots of problems. My invention solves those issues.”
Most new (and traditional) medtech material concoctions are designed to solve issues, obviously. But some take a unique approach to those problems. Consider Resomer, a family of lactide- and glycolide-based bioresorbable polyester polymers from German material development firm Evonik Industries AG. The polymers are used to manufacture biodegradable surgical screws, nails and plates that disintegrate in the body after a certain amount of time without causing any adverse effects. Resomer also is becoming a prime choice component in extended-release drug delivery systems; it is used, for instance, in Abbott Vascular’s drug-eluting bioresorbable stent (Absorb), which currently is available in Europe.
Certainly, the drogher nature of bioresorbable and bioabsorbable materials is endearing these substances to medtech engineers as the industry attempts to mimic Mother Nature’s handiwork. As one device expert noted, “The wide property range of bioabsorbable materials and their ability to carry drugs opens a door to many possibilities. And the material properties can be adjusted, from stiff to flexible. These allow conquering problems that nobody has a solution to, until now.”
Secant Medical Inc. has found a clever way around the body’s natural defense barriers with Regenerez, a bioresorbable elastomer developed by Robert Langer, Ph.D., at the Massachusetts Institute of Technology. Made from poly(glycerol sebacate), or PGS, the material can be customized for various applications—as scaffolding for bone repair, fibers for biotextiles, or coatings for grafts—and does not set off the human body’s immunological alarms.
Emily Ho, director and general manager of Advanced Biomaterials & Contract Device Services at Secant, spoke with Medical Product Outsourcing about Regenerez and medical device materials. Her conversation with the magazine follows:
MPO: Are any new materials being introduced (or recently have been introduced) to the medical device industry? What makes these new substances better than their predecessors (or those materials currently on the market)?
Emily Ho: Yes. Secant Medical is working with a bioresorbable resin called Regenerez, polyglycerol sebacate (PGS) polymer. When PGS degrades, it breaks down into natural metabolites with minimal local pH change. PGS can promote healing without an acute inflammatory response, and the native tissue results with minimal scar tissue. As a surface-eroding material, its degradation characteristics are more predictable than bulk eroders such as PGA and PLA, and there is more control over the loss of mechanical properties. Regenerez closely simulates the modulus of human tissue, thereby limiting the compliance mismatch issues seen with other materials; PGA and PLA are stiff materials that do not meet the natural compliance properties of tissue. In addition to mismatched physical properties, the degradation chemistry of lactides and glycolides creates a locally acidic environment that can induce an inflammatory response, thus delaying the natural healing process. PGA and PLA are also bulk-eroding materials, which means when they degrade, the device swells, an event that is followed by a reduction of mass and a significant decrease in mechanical properties. The performance of the device during degradation can result in an uncontrolled performance profile, which can lead to potential product failure.
MPO: Are long-established medical device design materials (such as metals) being replaced by other substances? In particular, what role is plastics playing in this trend?
Ho: Cost is a consideration. Polymers are relatively more cost effective compared to metal in terms of manufacturing and raw material cost. Polymers can be tuned to mimic the mechanical properties of natural tissue, and they are excellent shock absorbers that can be used in a wide range of orthopedics applications (which are traditionally made of metal). The new generation of polymers are much improved in terms of chemical and corrosion resistance. In addition, the capability of manufacturing clean polymers has dramatically improved. Lastly, many people are allergic to metals; thus, they cannot be treated with metallic implants.
MPO: What factors must be taken into consideration when selecting a material for medical devices?
Ho: Tissue compliance, fatigue resistance, and mechanical and chemical properties. When considering long-term performance, you need to think about how (or if) a material degrades, resorbs, swells. How does the body react to it? Will the material migrate once it is implanted in the body? We’re not fixing a wound; we’re fixing everything around it. The body is a very dynamic environment for materials, so we need to consider all the interactions that take place from one place to another inside the body.
MPO: What industry trends are driving the push for innovation in materials?
Ho: There is a need for materials that are resorbable and enable a faster patient recovery. Other trends driving innovation in materials include minimally invasive devices and combination products (materials that facilitate drug delivery).
MPO: How has the regulatory environment and cost impacted material innovation?
Ho: Clinical data requirements have dramatically increased costs incurred by medical device companies. Depending on the Class of the device, companies are required to have several years’ worth of clinical data, which costs time and much more money.
MPO: How are hospital acquired infections (HAIs) impacting material selection for medical devices (if at all)?
Ho: When an infection is acquired in a hospital (HAIs), insurance companies no longer cover the cost of all related treatments, thus becoming a heavy financial burden of each hospital. As a result, hospitals tend to discharge patients as soon as possible to reduce the HAI risk. This is also drives the growth of faster and minimally invasive procedures (such as robotics assisted surgical procedures) in the operating room. Most new devices are designed to use in minimally invasive procedures and promote fast recovery. These devices tend to very small, flexible and intricate, and usually are made with bio-polymer. Using minimally invasive combination products that integrate antimicrobials and an advanced healing capability, such as regeneration of the natural tissue, can also help prevent HAI.
MPO: Medical devices have evolved to the point now where they are being customized to individual patients. Are materials destined to follow suit? Are materials increasingly becoming tailored at the molecular level for specific needs? Please elaborate.
Ho: Customized materials can involve 3-D printing materials or it can mean the fine tuning of a product at the surgical bed. Regardless, manufacturers need to provide materials that offer custom capabilities; they don’t have a choice. At the macro level, providing a material that enables a surgeon to trim, tune, or cut on the surgical table offers more flexibility to achieve the right shape based on the need. Custom materials can also mean tailoring a material at the molecular level to meet a specific treatment need. For example, when you are working with a cardiovascular graft, the material needs to enhance endovascularization; while when you’re treating bone, there is a need for a material that enables natural remodeling for bone to promote growth.
Indeed, the material used most often to provide bodily comfort and protection is surprising researchers with its potential medical device bracing and pressure relieving applications. A new, high-performing auxetic version of foam developed by a Florida State University engineering professor for the U.S. Department of Veterans Affairs works counter-intuitively to the traditional material by becoming thicker rather than thinner when stretched. The innovation was part of the VA Innovation Initiative project, created to address the shortcomings of current prosthetic socket systems.
“We know what is not working with current products and technology, and what it is going to take to make it better,” Changchun “Chad” Zeng, Ph.D., told ScienceDaily. “For example, the socks that amputees currently use to attach prosthetic devices do not adjust to limb shape and volume, creating lots of problems. My invention solves those issues.”
Most new (and traditional) medtech material concoctions are designed to solve issues, obviously. But some take a unique approach to those problems. Consider Resomer, a family of lactide- and glycolide-based bioresorbable polyester polymers from German material development firm Evonik Industries AG. The polymers are used to manufacture biodegradable surgical screws, nails and plates that disintegrate in the body after a certain amount of time without causing any adverse effects. Resomer also is becoming a prime choice component in extended-release drug delivery systems; it is used, for instance, in Abbott Vascular’s drug-eluting bioresorbable stent (Absorb), which currently is available in Europe.
Certainly, the drogher nature of bioresorbable and bioabsorbable materials is endearing these substances to medtech engineers as the industry attempts to mimic Mother Nature’s handiwork. As one device expert noted, “The wide property range of bioabsorbable materials and their ability to carry drugs opens a door to many possibilities. And the material properties can be adjusted, from stiff to flexible. These allow conquering problems that nobody has a solution to, until now.”
Secant Medical Inc. has found a clever way around the body’s natural defense barriers with Regenerez, a bioresorbable elastomer developed by Robert Langer, Ph.D., at the Massachusetts Institute of Technology. Made from poly(glycerol sebacate), or PGS, the material can be customized for various applications—as scaffolding for bone repair, fibers for biotextiles, or coatings for grafts—and does not set off the human body’s immunological alarms.
Emily Ho, director and general manager of Advanced Biomaterials & Contract Device Services at Secant, spoke with Medical Product Outsourcing about Regenerez and medical device materials. Her conversation with the magazine follows:
MPO: Are any new materials being introduced (or recently have been introduced) to the medical device industry? What makes these new substances better than their predecessors (or those materials currently on the market)?
Emily Ho: Yes. Secant Medical is working with a bioresorbable resin called Regenerez, polyglycerol sebacate (PGS) polymer. When PGS degrades, it breaks down into natural metabolites with minimal local pH change. PGS can promote healing without an acute inflammatory response, and the native tissue results with minimal scar tissue. As a surface-eroding material, its degradation characteristics are more predictable than bulk eroders such as PGA and PLA, and there is more control over the loss of mechanical properties. Regenerez closely simulates the modulus of human tissue, thereby limiting the compliance mismatch issues seen with other materials; PGA and PLA are stiff materials that do not meet the natural compliance properties of tissue. In addition to mismatched physical properties, the degradation chemistry of lactides and glycolides creates a locally acidic environment that can induce an inflammatory response, thus delaying the natural healing process. PGA and PLA are also bulk-eroding materials, which means when they degrade, the device swells, an event that is followed by a reduction of mass and a significant decrease in mechanical properties. The performance of the device during degradation can result in an uncontrolled performance profile, which can lead to potential product failure.
MPO: Are long-established medical device design materials (such as metals) being replaced by other substances? In particular, what role is plastics playing in this trend?
Ho: Cost is a consideration. Polymers are relatively more cost effective compared to metal in terms of manufacturing and raw material cost. Polymers can be tuned to mimic the mechanical properties of natural tissue, and they are excellent shock absorbers that can be used in a wide range of orthopedics applications (which are traditionally made of metal). The new generation of polymers are much improved in terms of chemical and corrosion resistance. In addition, the capability of manufacturing clean polymers has dramatically improved. Lastly, many people are allergic to metals; thus, they cannot be treated with metallic implants.
MPO: What factors must be taken into consideration when selecting a material for medical devices?
Ho: Tissue compliance, fatigue resistance, and mechanical and chemical properties. When considering long-term performance, you need to think about how (or if) a material degrades, resorbs, swells. How does the body react to it? Will the material migrate once it is implanted in the body? We’re not fixing a wound; we’re fixing everything around it. The body is a very dynamic environment for materials, so we need to consider all the interactions that take place from one place to another inside the body.
MPO: What industry trends are driving the push for innovation in materials?
Ho: There is a need for materials that are resorbable and enable a faster patient recovery. Other trends driving innovation in materials include minimally invasive devices and combination products (materials that facilitate drug delivery).
MPO: How has the regulatory environment and cost impacted material innovation?
Ho: Clinical data requirements have dramatically increased costs incurred by medical device companies. Depending on the Class of the device, companies are required to have several years’ worth of clinical data, which costs time and much more money.
MPO: How are hospital acquired infections (HAIs) impacting material selection for medical devices (if at all)?
Ho: When an infection is acquired in a hospital (HAIs), insurance companies no longer cover the cost of all related treatments, thus becoming a heavy financial burden of each hospital. As a result, hospitals tend to discharge patients as soon as possible to reduce the HAI risk. This is also drives the growth of faster and minimally invasive procedures (such as robotics assisted surgical procedures) in the operating room. Most new devices are designed to use in minimally invasive procedures and promote fast recovery. These devices tend to very small, flexible and intricate, and usually are made with bio-polymer. Using minimally invasive combination products that integrate antimicrobials and an advanced healing capability, such as regeneration of the natural tissue, can also help prevent HAI.
MPO: Medical devices have evolved to the point now where they are being customized to individual patients. Are materials destined to follow suit? Are materials increasingly becoming tailored at the molecular level for specific needs? Please elaborate.
Ho: Customized materials can involve 3-D printing materials or it can mean the fine tuning of a product at the surgical bed. Regardless, manufacturers need to provide materials that offer custom capabilities; they don’t have a choice. At the macro level, providing a material that enables a surgeon to trim, tune, or cut on the surgical table offers more flexibility to achieve the right shape based on the need. Custom materials can also mean tailoring a material at the molecular level to meet a specific treatment need. For example, when you are working with a cardiovascular graft, the material needs to enhance endovascularization; while when you’re treating bone, there is a need for a material that enables natural remodeling for bone to promote growth.