Biomaterials
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Cutting edge developments in engineering of tissues, implants and devices allow for guidance and control of specific physiological structure-function relationships. Yet the engineering of functionally appropriate human-device interfaces represents an intractable challenge in the field. This leading opinion review outlines a set of current approaches as well as hurdles to design of interfaces that modulate transfer of information, i.a. forces, electrical potentials, chemical gradients and haptotactic paths, between endogenous and engineered body parts or tissues. ⋯ Functional barrier interfaces that control molecular and biophysical traffic between tissue compartments of joints are addressed in an example of the knee. Furthermore, we describe the engineering of gradients for interfaces between endogenous and engineered tissues as well as between electrodes that physically and electrochemically couple the nervous and musculoskeletal systems. Finally, to promote translation of newly developed technologies into products, protocols, and treatments that benefit the patients who need them most, regulatory and technical challenges and opportunities are addressed on hand from an example of an implant cum delivery device that can be used to heal soft and hard tissues, from brain to bone.
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With the high occurrence of cardiovascular disease and increasing numbers of patients requiring vascular access, there is a significant need for a small-diameter (<6 mm inner diameter) vascular graft that can provide long-term patency. Tissue engineering provides a very promising solution to this need. ⋯ This review summarizes the exciting work that has been reported on the application of adult stem cells to tissue engineered vascular grafts. Work in this area to date has employed bone marrow mononuclear progenitor cells, mesenchymal stem cells from various sources, and endothelial precursor cells.
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A vertebral fracture, whether originating from osteoporosis or trauma, can be the cause of pain, disability, deformation and neurological deficit. The treatment of vertebral compression fractures has, for many years until the advent of vertebroplasty, consisted of bedrest and analgesics. Vertebroplasty is a percutaneous technique during which bone cement is injected in a vertebral body to provide immediate pain relief by stabilization. ⋯ The clinical results of (balloon-) vertebroplasty are favorable with 85-95% of all patients experiencing immediate and long-lasting relief of pain. Serious complications are relatively rare but include neurological deficit and pulmonary embolism. In this paper, both vertebroplasty and balloon vertebroplasty and their respective indications, techniques and results are described in relation with the application and limitations of permanent and resorbable injectable bone cements.
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Animal models have been used extensively to investigate the biology of fracture healing and spinal fusion. The goal of each spinal fusion model is to try and reproduce the correct sequence of events during osseous healing in humans. Animal models allow us the capability of dialing in fusion rates and fusion parameters depending upon the study conditions. These models have become invaluable in assessing the clinical potential of emerging technologies such as recombinant growth factors and gene therapy.
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Glues and adhesives attach to a surface principally involving molecular attraction, whereas cements mostly work through mechanical interlocking. The adhesive and its degradation products must be biocompatible: chemical, clinical, legal, physical aspects are considered; the toxicity of even minor components must be extremely reduced. The idea of bone bonding using biological materials has been proposed by Gluck, in Berlin, more than a century ago. ⋯ Charnley used self-curing acrylic cement to bond a femoral head prosthesis into a femur. When adhesives are used to bond tissues, the polymer acts as a barrier between the growing edges and delay healing; the adhesive tends to be rapidly isolated from the bone by a fibrotic, non-adhesive capsule. No proof exists concerning the osteogenic potential of fibrin sealing (FS); its beneficial effect on bone formation has been questioned even if there is some evidence that FS should influence the early phases of bone repair and may help to solve the problem of reattachment of small osteocartilagenous fragments following joint trauma.