Biodegradable Polymers in Bone Tissue Engineering

Abstract

The use of degradable polymers in medicine largely started around the mid 20th century with their initial use as in vivo resorbing sutures. Thorough knowledge on this topic as been gained since then and the potential applications for these polymers were, and still are, rapidly expanding. After improving the properties of lactic acid-based polymers, these were no longer studied only from a scientific point of view, but also for their use in bone surgery in the 1990s. Unfortunately, after implanting these polymers, different foreign body reactions ranging from the presence of white blood cells to sterile sinuses with resorption of the original tissue were observed. This led to the misconception that degradable polymers would, in all cases, lead to inflammation and/or osteolysis at the implantation site. Nowadays, we have accumulated substantial knowledge on the issue of biocompatibility of biodegradable polymers and are able to tailor these polymers for specific applications and thereby strongly reduce the occurrence of adverse tissue reactions. However, the major issue of biofunctionality, when mechanical adaptation is taken into account, has hitherto been largely unrecognized. A thorough understanding of how to improve the biofunctionality, comprising biomechanical stability, but also visualization and sterilization of the material, together with the avoidance of fibrotic tissue formation and foreign body reactions, may greatly enhance the applicability and safety of degradable polymers in a wide area of tissue engineering applications. This review will address our current understanding of these biofunctionality factors, and will subsequently discuss the pitfalls remaining and potential solutions to solve these problems.

Carbon nanotube interaction with extracellular matrix proteins producing scaffolds for tissue engineering

“…4 Three years later dates the first evidence of successful study in tissue engineering when grafts were used to repair bones in Amsterdam; 5 however, only 225 years later the concept of "scaffold" was elaborated by Barth: 6 a porous matrix in which cells can infiltrate to regenerate the injured tissue. Nowadays, this concept has been reformulated to aggregate the idea that a scaffold should be able to determinate the fate of cells, guiding them to promote tissue regeneration.…”

Mg and Its Alloys for Biomedical Applications: Exploring Corrosion and Its Interplay with Mechanical Failure

“…In certain biomedical applications, especially fixators such as bone plates, screws, pins and stents, biomedical devices are required to stay inside the human body only for a restricted period, i.e., as long as bones heal. Thus, materials that ideally degrade in the same manner and speed as natural bone heals [10,47,48] are widely required to be utilized for these temporary devices. Biodegradable materials allow circumventing cumbersome second surgeries involving the removal of the old implant.…”

Stem Cell-Based Tissue Engineering for Bone Repair

“…In the creation of such scaffolds, controlling the degradable nature of the biomaterial is crucial [4,41]. Degradability ultimately relies on the chemical structure, architecture, and morphology of the scaffold, so a synthetic material that contains copolymers associated with crystalline materials are the most promising [4].…”

“…The most relevant of these effects is the interaction of the polymers with the host's immune system. Implantation of the polymers described above have caused immune reactions in some patients ranging from the release of large numbers of white blood cells, to resorption of the original tissue [4,41]. Therefore, greater understanding of the relationship between biocompatibility of a material before implantation, and its mechanical adaptation when placed inside the body needs to be further investigated.…”

“…Therefore, greater understanding of the relationship between biocompatibility of a material before implantation, and its mechanical adaptation when placed inside the body needs to be further investigated. Proper sterilization of the material without compromising biomechanical stability, in addition to possessing properties that inhibits fibrotic tissue formation and immune reaction will help to create a synthetic biomaterial that can be used safely for degradable tissue engineering scaffolds in bone [4,41].…”