In vitro response of human peripheral blood mononuclear cells to AISI 316L austenitic stainless steel subjected to nitriding and collagen coating treatments

Abstract

Surface modification treatments can be used to improve the biocompatibility of austenitic stainless steels. In the present research two different modifications of AISI 316L stainless steel were considered, low temperature nitriding and collagen-I coating, applied as single treatment or in conjunction. Low temperature nitriding produced modified surface layers consisting mainly of S phase, which enhanced corrosion resistance in PBS solution. Biocompatibility was assessed using human peripheral blood mononuclear cells (PBMC) in culture. Proliferation, lactate dehydrogenase (LDH) levels, release of cytokines (TNF-α, IL-1β, IL-12, IL-10), secretion of metalloproteinase (MMP)-9 and its inhibitor TIMP-1, and the gelatinolytic activity of MMP-9 were determined. While the 48-h incubation of PBMC with all the sample types did not negatively influence cell proliferation, LDH and MMP-9 levels, suggesting therefore a good biocompatibility, the release of the pro-inflammatory cytokines was always remarkable when compared to that of control cells. However, in the presence of the nitrided and collagen coated samples, the release of the pro-inflammatory cytokine IL-1β decreased, while that of the anti-inflammatory cytokine IL-10 increased, in comparison with the untreated AISI 316L samples. Our results suggest that some biological parameters were ameliorated by these surface treatments of AISI 316L.

From Austenitic Stainless Steel to Expanded Austenite-S Phase: Formation, Characteristics and Properties of an Elusive Metastable Phase

“…When plasma nitrided (400 • C, 500 Pa, 5 h) and collagen coated AISI 316L samples were put in contact with HUVEC, significant higher cell proliferation was observed after 5 days for this sample type, in comparison with that registered for samples untreated and collagen coated or subjected only to plasma nitriding treatment, and a smaller release of metalloproteinase (MMP)-2, related to extracellular matrix degradation, was detected [223]. Biocompatibility of AISI 316L untreated and plasma nitrided (400 • C, 500 Pa, 5 h) with or without collagen coating was also tested incubating the samples with human PBMC [230]. The results showed that proliferation, viability and MMP-9 secretion were not negatively affected by the contact with the sample types, but a remarkable increase of the secretion of some pro-inflammatory cytokines was registered, in comparison with control cells.…”

“…The authors observed the same good level of cytocompatibility for untreated and treated samples when proliferation, apoptosis and cytokine released by HUVEC were considered, while cytokine released by PBMC and the increase in adhesion molecules levels suggested that consequences were occurring on a metabolic point of view. Low temperature nitriding has been reported to be a suitable treatment to act as a substrate for collagen coating [223,224,230]. When plasma nitrided (400 • C, 500 Pa, 5 h) and collagen coated AISI 316L samples were put in contact with HUVEC, significant higher cell proliferation was observed after 5 days for this sample type, in comparison with that registered for samples untreated and collagen coated or subjected only to plasma nitriding treatment, and a smaller release of metalloproteinase (MMP)-2, related to extracellular matrix degradation, was detected [223].…”

“…In addition to aqueous solutions of NaCl, the nitrided samples also have an improved corrosion resistance when they are put in contact with chloride-ion saline solutions, as those used to simulate body fluids. When a S-phase layer forms, enhanced corrosion resistance has been shown by samples tested in Ringer's solution [218,229], phosphate-buffered saline (PBS) solution [223,224,230] and simulated body fluid (SBF) solution [231]. Lei and Zhu [229] tested AISI 316L and 1Cr18Ni9Ti, untreated and plasma source ion nitrided at 380 • C for 4 h, in Ringer's solutions at pH values in the range 3.5-7.2 at 37 • C, and they observed that the nitrided samples did not have pitting corrosion when the solution was at pH 7.2 and 5.5, due to the transpassivation solution of the passive films on the surface, while for pH 3.5 a passivation-pitting corrosion transition was registered, even if the pitting potential was higher than that of the untreated steels.…”

Preference and usage of intracanal medications during endodontic treatment

“…Lentulo spirals, due to their rotation motion, are prone to fracture with in the root canal system, 49 especially where there is reduced corrosion resistance due to repeated sterilization cycles. 50 Such an adverse outcome may further complicate endodontic treatment. 51 …”

In Vitro Response of Human Peripheral Blood Mononuclear Cells (PBMC) to Collagen Films Treated with Cold Plasma

“…The non-specific inflammatory response to implanted devices varies depending on their surface physicochemical properties, including surface chemistry, morphology and mechanics [12,13,14,15,16]. These properties affect the type, the quantity and the conformation of the adsorbed proteins, which determines the following interaction with adhesion receptors present on inflammatory cell populations, instigates a cascade of responses that are integral in determining the cellular driven inflammatory response, and constitutes the major cellular recognition system for implant materials [17,18].…”