Role of polypeptides in the treatment and diagnosis of osteoporosis

Fibrinogen and fibrin based micro and nano scaffolds incorporated with drugs, proteins, cells and genes for therapeutic biomedical applications

Over the past two decades, many types of natural and synthetic polymer-based micro- and nanocarriers, with exciting properties and applications, have been developed for application in various types of tissue regeneration, including bone, cartilage, nerve, blood vessels, and skin. The development of suitable polymers scaffold designs to aid the repair of specific cell types have created diverse and important potentials in tissue restoration. Fibrinogen (Fbg)- and fibrin (Fbn)-based micro- and nanostructures can provide suitable natural matrix environments. Since these primary materials are abundantly available in blood as the main coagulation proteins, they can easily interact with damaged tissues and cells through native biochemical interactions. Fbg- and Fbn-based micro and nanostructures can also be consecutively furnished/or encapsulated and specifically delivered, with multiple growth factors, proteins, and stem cells, in structures designed to aid in specific phases of the tissue regeneration process. The present review has been carried out to demonstrate the progress made with micro and nanoscaffold applications and features a number of applications of Fbg- and Fbn-based carriers in the field of biomaterials, including the delivery of drugs, active biomolecules, cells, and genes, that have been effectively used in tissue engineering and regenerative medicine.

Muscarinic acetylcholine receptors present in human osteoblast and bone tissue

Acetylcholine is the predominant neurotransmitter in the neuromuscular junction, and a role in bone has been postulated. The expression of nicotinic receptors has been reported in osteoblasts, but the expression and function of muscarinic receptor in bone remain obscure. In this study, we investigated the expression and functional activities of muscarinic receptor subtypes in human osteoblast cell lines and animal and human bone tissue. The mRNA levels of muscarinic receptor subtypes were detected by reverse-transcription polymerase chain reaction. We found that muscarinic subtypes m1, m2, m3, m4, and m5 were expressed at different levels in human osteosarcoma HOS cells, rat femur, and human rib bone tissue; m1, m4, m5 were in cultured mouse femur bone cells and cultured mouse calvarial bone cells; m2, m3, m4 were in bovine bone. The mRNA of neuronal markers, light-, medium- and heavy-neurofilament, was not found in human bone tissues to exclude the possible contamination from neuronal tissue. Methacholine induced an elevation in cytosolic calcium concentration and proliferation in HOS cells. Both effects were blocked by atropine. We conclude that muscarinic receptor is present in bone tissue to evoke calcium signaling and modulate cell proliferation. Different muscarinic receptor subtypes are distributed in various parts of the animal skeletal system including the different species and bone portions. Bone remodeling involving osteoblast proliferation leads the possibilities that muscarinic receptor may play roles in bone remodeling.