Chandler-Loop surveyed blood compatibility and dynamic blood triggered degradation behavior of Zn-4Cu alloy and Zn.

Zinc (Zn) and its alloys have been considered promising absorbable metals for medical implants. However, the dynamic interaction between Zn-based materials and human blood after implantation remains unclear. In this study, a modified Chandler-Loop system was applied to assess the blood compatibility and initial degradation behavior of a Zn-4.0Cu (wt%) alloy (Zn-4Cu) and Zn with human peripheral blood under circulation conditions. In this dynamic in vitro model, the Zn-4Cu and Zn showed sufficient blood compatibility. The numbers of erythrocytes, platelets, and leukocytes were not significantly altered, and appropriate activations of the coagulation and complement system were observed. Concerning initial degradation behavior, the product layers formed on the surfaces comprise a mixture of organic and inorganic compounds while the inorganic constituents decrease toward the outer surface. Considering the corrosion morphology and electrochemical behaviors, Zn-4Cu exhibited milder and more uniform degradation than Zn. Additionally, long-term degradation tests of 28 days in human peripheral blood, human serum, and Dulbecco's phosphate-buffered saline (DPBS) demonstrated that the Zn-4Cu showed relatively uniform degradation in blood and serum. On the contrary, in DPBS, severe localized corrosion appeared along the grain boundary of the secondary phase, which was likely attributed to the acceleration of galvanic corrosion. The Zn was found with localized corrosion impeded in the blood albeit with apparently developed deep pitting holes in the serum and DPBS.

Blood compatibility of magnesium and its alloys.

RATIONALE: Blood compatibility analysis in the field of biomaterials is a highly controversial topic. Especially for degradable materials like magnesium and its alloys no established test methods are available. OBJECTIVE: The purpose of this study was to apply advanced test methodology for the analysis of degrading materials to get a mechanistic insight into the corrosion process in contact with human blood and plasma. METHODS AND RESULTS: Pure magnesium and two magnesium alloys were analysed in a modified Chandler-Loop setup. Standard clinical parameters were determined, and a thorough analysis of the resulting implant surface chemistry was performed. The contact of the materials to blood evoked an accelerated inflammatory and cell-induced osteoconductive reaction. Corrosion products formed indicate a more realistic, in vivo like situation. CONCLUSIONS: The active regulation of corrosion mechanisms of magnesium alloys by different cell types should be more in the focus of research to bridge the gap between in vitro and in vivo observations and to understand the mechanism of action. This in turn could lead to a better acceptance of these materials for implant applications. STATEMENT OF SIGNIFICANCE: The presented study deals with the first mechanistic insights during whole human blood contact and its influence on a degrading magnesium-based biomaterial. The combination of clinical parameters and corrosion layer analysis has been performed for the first time. It could be of interest due to the intended use of magnesium-based stents and for orthopaedic applications for clinical applications. An interest for the readers of Acta Biomaterialia may be given, as one of the first clinically approved magnesium-based devices is a wound-closure device, which is in direct contact with blood. Moreover, for orthopaedic applications also blood contact is of high interest. Although this is not the focus of the manuscript, it could help to rise awareness for potential future applications.

Protective effect of nicotinic acid amide on human umbilical cord mesen-chymal stem cells / 中国病理生理杂志

AIM:Toinvestigatetheeffectofnicotinicacidamide(NAA)ontheinfusiondamageofhuman umbilical cord mesenchymal stem cells ( hUC-MSCs) under the condition of instant blood-mediated inflammatory reaction ( IBMIR) .METHODS:Normal peripheral blood without anticoagulant at volume of 2.7 mL was mixed with 0.3 mL phys-iological saline (as blank group), CFSE labeled hUC-MSCs (1 ×106 cells in 0.3 mL as MSC group) and CFSE labeled hUC-MSCs (1 ×106 cells in 0.3 mL) preprocessed with NAA at concentration of 10 mmol/L for 24 h ( as MSC+NAA group) , respectively.The mixture was immediately injected into the improved Chandler Loop model, placed in 37℃water bath, and then started the peristaltic pump at the speed of 20 mL/min for 1 h.The number of CFSE labeled hUC-MSCs, platelets, white blood cells were counted and the concentration of complement C3a was measured before and after cycling, respectively.RESULTS: After 1 h circulation, the platelet dissipation rate were ( 29.96 ±10.88 )% in blank group, (77.76 ±19.29)% in MSC group all and (50.13 ±18.10)% in MSC +NAA group; and the leukocyte counts were (37.82 ±13.81)%in blank group, (64.57 ±17.08)% in MSC group and (41.52 ±17.26)% in MSC+NAA group. Compared with blank group, the differences of the dissipation rates in MSC group and MSC+NAA group all had statistical significance.The hUC-MSCs relative survival rate in MSC+NAA group was higher than that in MSC group.C3a concentra-tions in blank group, MSC group and MSC+NAA group were (206.27 ±58.10), (230.47 ±39.61) and (208.37 ± 40.66) μg/L, respectively.CONCLUSION:Co-circulating the mixture of hUC-MSCs with normal peripheral blood with-out anticoagulant in the improved Chandler Loop for 1 h depletes a large number of hUC-MSCs and blood components, and increases C3a, suggesting that this model can induce IBMIR.NAA has a protective effect on the hUC-MSCs in the infusion damage by inhibiting IBMIR, reducing the wastage of the blood components and enhancing the survival rate of the hUC-MSCs.