An appropriate cellular response to implanted surfaces is essential for tissue regeneration and integration. It is well described that implanted materials are immediately coated with proteins from blood and interstitial fluids, and it is through this adsorbed layer that cells sense foreign surfaces. Hence, it is the adsorbed proteins, rather than the surface itself, to which cells initially respond. Diverse studies using a range of materials have demonstrated the pivotal role of extracellular adhesion proteins--fibronectin and vitronectin in particular--in cell adhesion, morphology, and migration. These events underlie the subsequent responses required for tissue repair, with the nature of cell surface interactions contributing to survival, growth, and differentiation. The pattern in which adhesion proteins and other bioactive molecules adsorb thus elicits cellular reactions specific to the underlying physicochemical properties of the material. Accordingly, in vitro studies generally demonstrate favorable cell responses to charged, hydrophilic surfaces, corresponding to superior adsorption and bioactivity of adhesion proteins. This review illustrates the mediation of cell responses to biomaterials by adsorbed proteins, in the context of osteoblasts and selected materials used in orthopedic implants and bone tissue engineering. It is recognized, however, that the periimplant environment in vivo will differ substantially from the cell-biomaterial interface in vitro. Hence, one of the key issues yet to be resolved is that of the interface composition actually encountered by osteoblasts within the sequence of inflammation and bone regeneration.

Mediation of Biomaterial–Cell Interactions by Adsorbed Proteins: A Review

Platelets are known for their role in haemostasis where they help prevent blood loss at sites of vascular injury. To do this, they adhere, aggregate and form a procoagulant surface leading to thrombin generation and fibrin formation. Platelets also release substances that promote tissue repair and influence the reactivity of vascular and other blood cells in angiogenesis and inflammation. They contain storage pools of growth factors including PDGF, TGF-β and VEGF as well as cytokines including proteins such as PF4 and CD40L. Chemokines and newly synthesised active metabolites are also released. The fact that platelets secrete growth factors and active metabolites means that their applied use can have a positive influence in clinical situations requiring rapid healing and tissue regeneration.Their administration in fibrin clot or fibrin glue provides an adhesive support that can confine secretion to a chosen site. Additionally, the presentation of growth factors attached to platelets and/or fibrin may result in enhanced activity over recombinant proteins. Dental implant surgery with guided bone regeneration is one situation where an autologous platelet-rich clot clearly accelerates ossification after tooth extraction and/or around titanium implants. The end result is both marked reductions in the time required for implant stabilisation and an improved success rate. Orthopaedic surgery, muscle and/or tendon repair, reversal of skin ulcers, hole repair in eye surgery and cosmetic surgery are other situations where autologous platelets accelerate healing. Our aim is to review these advances and discuss the ways in which platelets may provide such unexpected beneficial therapeutic effects.

Autologous platelets as a source of proteins for healing and tissue regeneration

https://www.zora.uzh.ch/id/eprint/44154/1/Rabe1.pdf

Understanding protein adsorption phenomena at solid surfaces

Biomaterial-associated thrombosis: roles of coagulation factors, complement, platelets and leukocytes

Kinetic analysis of monoclonal antibody-antigen interactions with a new biosensor based analytical system.

A solid-phase enzyme-linked immunospot (ELISPOT) assay for enumeration of specific antibody-secreting cells

Implantation of hydrophilic and hydrophobic titanium discs in rat tibia: cellular reactions on the surfaces during the first 3 weeks in bone

Kinetics of antigen-antibody reactions at solid-liquid interfaces.

A new method for identification and localization of organic molecules in biological samples is described. The method involves making an imprint of a biological sample on a silver (Ag) surface and subsequent analysis of the imprint by imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS). Using this method, detection of unfragmented, Ag cationized molecules at a spatial resolution of <0.5 μm is possible. We have used the method to study the spatial distribution of phosphatidylcholine and cholesterol in blood cells adhering to a glass surface. The TOF-SIMS images show that cholesterol is preferentially located in the plasma membrane, whereas the phosphocholine shows highest concentration in the nuclear membrane. Scanning electron microscopy and fluorescence microscopy images show that the amount of transferred material during the imprinting process can be controlled by varying the imprinting pressure and pretreatment of the cell substrate prior to imprinting.

Imaging of membrane lipids in single cells by imprint-imaging time-of-flight secondary ion mass spectrometry.

Interactions between human whole blood and modified TiO2-surfaces : Influence of surface topography and oxide thickness on leukocyte adhesion and activation

Håkan Nygren

Papers

A solid-phase enzyme-linked immunospot (ELISPOT) assay for enumeration of specific antibody-secreting cells

Implantation of hydrophilic and hydrophobic titanium discs in rat tibia: cellular reactions on the surfaces during the first 3 weeks in bone

Kinetics of antigen-antibody reactions at solid-liquid interfaces.

Imaging of membrane lipids in single cells by imprint-imaging time-of-flight secondary ion mass spectrometry.

Interactions between human whole blood and modified TiO2-surfaces : Influence of surface topography and oxide thickness on leukocyte adhesion and activation