Bone Regeneration Based on Tissue Engineering Conceptions – A 21st Century Perspective

The role of Bone Tissue Engineering in the field of Regenerative Medicine has been the topic of substantial research over the past two decades. Technological advances have improved orthopaedic implants and surgical techniques for bone reconstruction. However, improvements in surgical techniques to reconstruct bone have been limited by the paucity of autologous materials available and donor site morbidity. Recent advances in the development of biomaterials have provided attractive alternatives to bone grafting expanding the surgical options for restoring the form and function of injured bone. Specifically, novel bioactive （second generation） biomaterials have been developed that are characterised by controlled action and reaction to the host tissue environment, whilst exhibiting controlled chemical breakdown and resorption with an ultimate replacement by regenerating tissue. Future generations of biomaterials （third generation） are designed to be not only osteo- conductive but also osteoinductive, i.e. to stimulate regeneration of host tissues by combining tissue engineer- ing and in situ tissue regeneration methods with a focus on novel applications. These techniques will lead to novel possibilities for tissue regeneration and repair. At present, tissue engineered constructs that may find future use as bone grafts for complex skeletal defects, whether from post-traumatic, degenerative, neoplastic or congenital/developmental ＂origin＂ require osseous reconstruction to ensure structural and functional integrity. Engineering functional bone using combinations of cells, scaffolds and bioactive factors is a promising strategy and a particular feature for future development in the area of hybrid materials which are able to exhibit suitable biomimetic and mechanical properties. This review will discuss the state of the art in this field and what we can expect from future generations of bone regeneration concepts.

Unravelling the physicochemical and antimicrobial mechanisms of human serum albumin/tannic acid coatings for medical-grade polycaprolactone scaffolds

Biofilm-related biomaterial infections are notoriously challenging to treat and can lead to chronic infection and persisting inflammation.To date,a large body of research can be reviewed for coatings which potentially prevent bacterial infection while promoting implant integration.Yet only a very small number has been translated from bench to bedside.This study provides an in-depth analysis of the stability,antibacterial mechanism,and biocompatibility of medical grade polycaprolactone(mPCL),coated with human serum albumin(HSA),the most abundant protein in blood plasma,and tannic acid(TA),a natural polyphenol with antibacterial properties.Molecular docking studies demonstrated that HSA and TA interact mainly through hydrogen-bonding,ionic and hydrophobic interactions,leading to smooth and regular assemblies.In vitro bacteria adhesion testing showed that coated scaffolds maintained their antimicrobial properties over 3 days by significantly reducing S.aureus colonization and biofilm formation.Notably,amplitude modulation-frequency modulation(AMFM)based viscoelasticity mapping and transmission electron microscopy(TEM)data suggested that HSA/TA-coatings cause morphological and mechanical changes on the outer cell membrane of s.aureus leading to membrane disruption and cell death while proving non-toxic to human primary cells.These results support this antibiotic-free approach as an effective and biocompatible strategy to prevent biofilm-related biomaterial infections.