An in vivo investigation of the biocompatibility and osseointegration characteristics of porous NiTiAg alloys

Introduction. Porous nickel-titanium (NiTi) alloys are attracting attention as implant materials due to their combination of mechanical compatibility with bone tissue and osteointegration capacity. The addition of silver nanoparticles (AgNPs) can alter the structural and phase state and surface characteristics of the material, but its biological behavior in vivo remains insufficiently studied.

Aim: To assess the biocompatibility and osseointegration potential of porous NiTiAg alloys synthesized by self-propagating hightemperature synthesis (HSS).

Material and Methods. NiTiAg alloys with 0.5 at. % AgNPs were studied by X-ray phase analysis and mechanical testing to evaluate their phase composition and properties. For the in vivo experiment, implants were placed in the cranial bone region of Balb/c mice (n = 10) for 14 days. Histological analysis was performed using hematoxylin-eosin, von Kossa staining, alizarin red S, and immunohistochemistry for osteopontin (Opn). Osteogenic differentiation of mesenchymal stem cells (MSCs) in vivo was studied on the alloy surface. The state of the immune response was assessed by the leukocyte profile.

Results. The alloys had a low modulus of elasticity and strength comparable to bone tissue. In the implantation area, preserved bone architecture, the formation of a vascularized connective tissue capsule, and the absence of an inflammatory response were observed. Staining demonstrated active mineralization and the participation of osteoblasts in the formation of new bone matrix. Opn expression indicated active osteogenesis. MSCs in vivo completely differentiated into osteoblasts with the formation of a calcium matrix. The leukocyte profile remained within physiological limits.

Discussion. The data obtained indicate that porous NiTiAg alloys are biocompatible, osteoconductive, and have low immunogenicity. The introduction of AgNPs does not have a negative effect on cells and tissues and also allows the required biocompatibility and osseointegration parameters of the material to be maintained. The material can be considered a promising basis for the creation of implants that promote bone tissue regeneration and reduce the risk of infectious complications.

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