Apoptosis and plastic surgery

Apoptosis in bone for tissue engineering

Bone loss due to congenital defects, trauma, improper fracture fixation, metabolic disturbances, infections, or after tumor resection represents a major clinical problem in head and neck surgery. To address these issues, different types of scaffolds, growth factors and cell sources -- alone or in various combinations -- have been applied for development of bioartificial bone tissues. Although these applications have received increasing interest, use of autologous bone grafts is still considered as the gold standard for tissue repair. Despite progress in some areas of tissue regeneration, significant translation into clinical practice has not been achieved. Reasons for this impass include rejection of engineered tissue implants by the immune system, limited blood supply, or morbidity of the donor site. During the process of bone regeneration, approximately 50-70% of osteoblasts undergo apoptosis. Apoptosis is a naturally occurring cell death pathway induced in a variety of cell types and is associated with caspase activation or caspase mediation. It is recognized as an important component of embryogenesis and tissue morphogenesis and, in adult skeletons, it contributes substantially to physiological bone turnover, repair, and regeneration. Intracellular mechanisms are orchestrated by a variety of proteins, the interplay of which seems to vary, depending on the differentiation state of the cell or the current status of the tissue. Closing gaps in current knowledge of the apoptosis of bone and understanding the mechanisms of cell death in tissue engineered bone will improve results in the translation from bench to bedsite. This review aims to provide a broad overview of the current general concepts in apoptosis with a special focus on its regulation in osteoblasts and its significance for bone tissue engineering.

Autologous Lipofilling: Coenzyme Q10 Can Rescue Adipocytes from Stress-Induced Apoptotic Death

BACKGROUND

Autologous fat transplantation (or lipofilling) is an excellent technique for correction of cosmetic defects. The success of the procedure relies strongly on the techniques of harvesting and transferring viable adipocytes. The purpose of this study was to evaluate effects of two harvesting methods and coenzyme Q10 on the viability and apoptotic death of adipocytes collected for autologous lipofilling.

METHODS

Human adipose tissue from six patients was collected by Luer-Lok syringe according to Coleman's technique or by means of an aspirator with a 680-mmHg vacuum. Half of each sample collected using Coleman's technique was treated with 10 muM Coenzyme Q10, and the other half served as untreated control. Viability and apoptosis were assessed by immunoenzymatic, biochemical, and morphological methods.

RESULTS

The harvesting of adipose tissue by aspirator reduced the viability and increased apoptotic death significantly more than harvesting tissue using Coleman's technique. Biochemical and morphological analyses confirmed that treatment of adipose tissue with coenzyme Q10 reduced and even inhibited apoptotic death of harvested adipocytes.

CONCLUSION

Coenzyme Q10 can rescue adipocytes from stress-induced apoptotic death.

Diabetes-enhanced inflammation and apoptosis--impact on periodontal pathology

Diabetes, particularly type 2 diabetes, is a looming health issue with many ramifications. Because diabetes alters the cellular microenvironment in many different types of tissues, it causes myriad untoward effects, collectively referred to as 'diabetic complications'. Two cellular processes affected by diabetes are inflammation and apoptosis. This review discusses how diabetes-enhanced inflammation and apoptosis may affect the oral environment. In particular, dysregulation of tumor necrosis factor and the formation of advanced glycation products, both of which occur at higher levels in diabetic humans and animal models, potentiate inflammatory responses and induce apoptosis of matrix-producing cells. The enhanced loss of fibroblasts and osteoblasts through apoptosis in diabetics could contribute to limited repair of injured tissue, particularly when combined with other known deficits in diabetic wound-healing. These findings may shed light on diabetes-enhanced risk of periodontal diseases.

Biological and biophysical principles in extracorporal bone tissue engineering

The aim of this review is to characterise the biological and biophysical background of in vitro bone tissue engineering. The paper focuses on basic principles in extracorporal engineering of bone-like tissues, considering parameters such as scaffold design, tissue construction, bioreactors, and cell stimulation in vivo and in vitro. Scaffolds have a key function concerning cellular invasion and bone formation. The intra-architectural scaffold geometry, as well as the scaffold material, play an important role in the process of bone regeneration. Various types of bioreactors have been tested for their utility in bone substitute fabrication that is clinically effective and reproducible. Sophisticated bioreactor systems are those that mimic the three-dimensional morphology and the mechanical situation of bones. Mechanical stimulation as well as other biophysical stimuli appear to be critical factors for proliferation and differentiation of bone cells and for bone mineral and structure formation. Furthermore an enhancement of bone regeneration by application of chemical stimulation factors is discussed.

The role of apoptosis in oral disease: mechanisms; aberrations in neoplastic, autoimmune, infectious, hematologic, and developmental diseases; and therapeutic opportunities

Apoptosis is a genetically programmed form of cell death, which primarily functions to eliminate senescent or altered cells that are useless or harmful for the multicellular organism. Contrary to necrosis, apoptosis represents a physiologic cellular mechanism, normal function and control of which are critical for the development and homeostasis of multicellular organisms. In contrast, aberrations of the apoptotic mechanisms that cause excessive or deficient programmed cell death have been linked to a wide array of pathologic conditions. This review briefly summarizes the major apoptotic pathways and molecules and presents the most important oral diseases that are related to dysregulation of apoptosis. Knowledge of the association between aberrations in apoptotic mechanisms and human pathology hopefully will be implemented for the design of improved diagnostic and prognostic assays and the development of novel, more efficient, therapeutic strategies.