Osteocyte pericellular and perilacunar matrices as markers of bone-implant mechanical integrity

To develop durable bone healing strategies through improved control of bone repair,it is of critical importance to understand the mechanisms of bone mechanical integrity when in contact with biomaterials and implants.Bone mechanical integrity is defined here as the adaptation of structural properties of remodeled bone in regard to an applied mechanical loading.Accordingly,the authors present why future investigations in bone repair and regeneration should emphasize on the matrix surrounding the osteocytes.Osteocytes are mechanosensitive cells considered as the orchestrators of bone remodeling,which is the biological process involved in bone homeostasis.These bone cells are trapped in an interconnected porous network,the lacunocanalicular network,which is embedded in a bone mineralized extracellular matrix.As a consequence of an applied mechanical loading,the bone deformation results in the deformation of this lacunocanalicular network inducing a shift in interstitial fluid pressure and velocity,thus resulting in osteocyte stimulation.The material environment surrounding each osteocyte,the so called perilacunar and pericellular matrices properties,define its mechanosensitivity.While this mechanical stimulation pathway is well known,the laws used to predict bone remodeling are based on strains developing at a tissue scale,suggesting that these strains are related to the shift in fluid pressure and velocity at the lacunocanalicular scale.While this relationship has been validated through observation in healthy bone,the fluid behavior at the bone-implant interface is more complex.The presence of the implant modifies fluid behavior,so that for the same strain at a tissue scale,the shift in fluid pressure and velocity will be different than in a healthy bone tissue.In that context,new markers for bone mechanical integrity,considering fluid behavior,have to be defined.The viewpoint exposed by the authors indicates that the properties of the pericellular and the perilacunar matrices have to be systematically investigated and used as structural markers of fluid behavior in the course of bone biomaterial development.

Modification of polyetheretherketone(PEEK)physical features to improve osteointegration

Polyetheretherketone(PEEK)has been widely applied in orthopedics because of its excellent mechanical properties,radiolucency,and biocompatibility.However,the bioinertness and poor osteointegration of PEEK have greatly limited its further application.Growing evidence proves that physical factors of implants,including their architecture,surface morphology,stiffness,and mechanical stimulation,matter as much as the composition of their surface chemistry.This review focuses on the multiple strategies for the physical modification of PEEK implants through adjusting their architecture,surface morphology,and stiffness.Many research findings show that transforming the architecture and incorporating reinforcing fillers into PEEK can affect both its mechanical strength and cellular responses.Modified PEEK surfaces at the macro scale and micro/nano scale have positive effects on cell-substrate interactions.More investigations are necessary to reach consensus on the optimal design of PEEK implants and to explore the efficiency of various functional implant surfaces.Soft-tissue integration has been ignored,though evidence shows that physical modifications also improve the adhesion of soft tissue.In the future,ideal PEEK implants should have a desirable topological structure with better surface hydrophilicity and optimum surface chemistry.

Treatment of Bone Marrow Failure Syndrome with Integrated Traditional and Western Medicine

Aplastic anemia （AA） and myelodysplastic syndrome （MDS） are both included in the bone marrow failure syndromes （BMFS）. AA is a group of diseases characterized by hematopoietic stem/progenitor cell damage, oerioheral blood cvtooenia, andclinical manifestations including anemia, bleeding and infection, which eventually lead to bone marrow failure. The incidence rate of AA in China is 7.4/10^6, higher than that in Western countries, among which the morbidity of acute AA and chronic AA （CAA） is 1.4/10^6 and 6.0/10^6, respectively.