Correlation between biological responses in vitro and in vivo to Ca-doped sol-gel coatings assessed using proteomic analysis.

Poor correlation between the results of in vitro testing and the subsequent in vivo experiments hinders the design of biomaterials. Thus, new characterisation methods are needed. This study used proteomic and histological techniques to analyse the effects of Ca-doped biomaterials in vitro and in vivo and verify the correlation between the two systems. The sol-gel route was employed to synthesise coatings functionalised with 0.5 and 5 wt% of CaCl2. Morphology of the coatings was examined using SEM; the Ca2+ ion release from the materials was analysed by means of ICP-AES spectroscopy. The osteogenic and inflammatory responses were inspected in vitro in human osteoblasts (HOb) and TPH-1 monocytes. The in vivo experiments used a rabbit model. The nLC-MS/MS-based proteomic methods were utilised to analyse the proteins adhering to the material samples incubated with human serum or examine protein expression in the tissues close to the implants. Ca-doped biomaterials caused a remarkable increase in the adsorption of coagulation-related proteins, both in vitro (PLMN, THRB, FIBA and VTNC) and in vivo (FBLN1, G1U978). Enhanced affinity to these materials was also observed for proteins involved in inflammation (CO5, C4BPA, IGHM and KV302 in vitro; CARD6, DDOST and CD14 in vivo) and osteogenic functions (TETN, PEDF in vitro; FBN1, AHSG, MYOC in vivo). The results obtained using different techniques were well matched, with a good correlation between the in vitro and in vivo experiments. Thus, the proteomic analysis of biological responses to biomaterials in vitro is a useful tool for predicting their impact in vivo.

Bioactive zinc-doped sol-gel coating modulates protein adsorption patterns and in vitro cell responses.

Zinc is an essential element with an important role in stimulating the osteogenesis and mineralization and suppressing osteoclast differentiation. In this study, new bioactive ZnCl2-doped sol-gel materials were designed to be applied as coatings onto titanium. The biomaterials were physicochemically characterized and the cellular responses evaluated in vitro using MC3T3-E1 osteoblasts and RAW264.7 macrophages. The effect of Zn on the adsorption of human serum proteins onto the material surface was evaluated through nLC-MS/MS. The incorporation of Zn did not affect the crosslinking of the sol-gel network. A controlled Zn2+ release was obtained, reaching values below 10 ppm after 21 days. The materials were no cytotoxic and lead to increased gene expression of ALP, TGF-ß, and RUNX2 in the osteoblasts. In macrophages, an increase of IL-1ß, TGF-ß, and IL-4 gene expression was accompanied by a reduced TNF-α liberation. Proteomic results showed changes in the adsorption patterns of proteins associated with immunological, coagulative, and regenerative functions, in a Zn dose-dependent manner. The variations in protein adsorption might lead to the downregulation of the NF-κB pathway, thus explain the observed biological effects of Zn incorporation into biomaterials. Overall, these coatings demonstrated their potential to promote bone tissue regeneration.

Complement proteins regulating macrophage polarisation on biomaterials.

One of the events occurring when a biomaterial is implanted in an host is the protein deposition onto its surface, which might regulate cell responses. When a biomaterial displays a compromised biocompatibility, distinct complement pathways can be activated to produce a foreign body reaction. In this article, we have designed different types of biomaterial surfaces to study the inflammation process. Here, we used different concentrations of (3-glycidoxypropyl)-trimethoxysilane (GPTMS), an organically-modified alkoxysilane as a precursor for the synthesis of various types of sol-gel materials functionalizing coatings for titanium implants to regulate biological responses. Our results showed that greater GPTMS surface concentrations induced greater secretion of TNF-α and IL-10 on RAW 264.7 macrophages. When implanted into rabbit tibia, osseointegration decreased with higher GPTMS concentrations. Interestingly, higher deposition of complement-related proteins C-reactive protein (CRP) and ficolin-2 (FCN2), two main activators of distinct complement pathways, was observed. Taking all together, inflammatory potential increase seems to be GPTMS concentration-dependent. Our results show that a greater adsorption of complement proteins can condition macrophage polarization.

Proteomic analysis of calcium-enriched sol-gel biomaterials.

Calcium is an element widely used in the development of biomaterials for bone tissue engineering as it plays important roles in bone metabolism and blood coagulation. The Ca ions can condition the microenvironment at the tissue-material interface, affecting the protein deposition process and cell responses. The aim of this study was to analyze the changes in the patterns of protein adsorption on the silica hybrid biomaterials supplemented with different amounts of CaCl2, which can function as release vehicles. This characterization was carried out by incubating the Ca-biomaterials with human serum. LC-MS/MS analysis was used to characterize the adsorbed protein layers and compile a list of proteins whose affinity for the surfaces might depend on the CaCl2 content. The attachment of pro- and anti-clotting proteins, such as THRB, ANT3, and PROC, increased significantly on the Ca-materials. Similarly, VTNC and APOE, proteins directly involved on osteogenic processes, attached preferentially to these surfaces. To assess correlations with the proteomic data, these formulations were tested in vitro regarding their osteogenic and inflammatory potential, employing MC3T3-E1 and RAW 264.7 cell lines, respectively. The results confirmed a Ca dose-dependent osteogenic and inflammatory behavior of the materials employed, in accordance with the protein attachment patterns.

The effect of strontium incorporation into sol-gel biomaterials on their protein adsorption and cell interactions.

It is known strontium can both inhibit the osteoclast formation and stimulate the osteoblast maturation, so biomaterials containing this element can favour bone structure stabilisation. The addition of Sr to biomaterials could affect their interactions with proteins and cells. Here, a silica-hybrid sol-gel network doped with different amounts of SrCl2 and applied as coatings on titanium discs was examined. in vitro analysis was performed to determine the potential effect of Sr in the coatings, showing enhanced gene expression of osteogenic markers (alkaline phosphatase and transforming growth factor-ß) in MC3T3-E1 incubated with Sr-doped biomaterials. The examination of inflammatory markers (tumour necrosis factor-α and interleukin 10) in RAW 264.7 macrophages revealed an anti-inflammatory potential of these materials. Proteins adsorbed onto the coatings incubated with human serum (3 h at 37 °C) were also analysed; mass spectrometry was used to characterise the proteins adhering to materials with different Sr content. Adding Sr to the coatings increased their affinity to APOE and VTNC proteins (associated with anti-inflammatory and osteogenic functions). Moreover, the proteins involved in coagulation processes, such as prothrombin, were more abundant on the coatings containing Sr than on the base sol-gel surfaces. Correlations between gene expression and proteomic results were also examined.

Osseointegration mechanisms: a proteomic approach.

The prime objectives in the development of biomaterials for dental applications are to improve the quality of osseointegration and to short the time needed to achieve it. Design of implants nowadays involves changes in the surface characteristics to obtain a good cellular response. Incorporating osteoinductive elements is one way to achieve the best regeneration possible post-implantation. This study examined the osteointegrative potential of two distinct biomaterials: sandblasted acid-etched titanium and a silica sol-gel hybrid coating, 70% MTMOS-30% TEOS. In vitro, in vivo, and proteomic characterisations of the two materials were conducted. Enhanced expression levels of ALP and IL-6 in the MC3T3-E1 cells cultured with coated discs, suggest that growing cells on such surfaces may increase mineralisation levels. 70M30T-coated implants showed improved bone growth in vivo compared to uncoated titanium. Complete osseointegration was achieved on both. However, coated implants displayed osteoinductive properties, while uncoated implants demonstrated osteoconductive characteristics. Coagulation-related proteins attached predominantly to SAE-Ti surface. Surface properties of the material might drive the regenerative process of the affected tissue. Analysis of the proteins on the coated dental implant showed that few proteins specifically attached to its surface, possibly indicating that its osteoinductive properties depend on the silicon delivery from the implant.

Bioactive potential of silica coatings and its effect on the adhesion of proteins to titanium implants.

There is an ever-increasing need to develop dental implants with ideal characteristics to achieve specific and desired biological response in the scope of improve the healing process post-implantation. Following that premise, enhancing and optimizing titanium implants through superficial treatments, like silica sol-gel hybrid coatings, are regarded as a route of future research in this area. These coatings change the physicochemical properties of the implant, ultimately affecting its biological characteristics. Sandblasted acid-etched titanium (SAE-Ti) and a silica hybrid sol-gel coating (35M35G30T) applied onto the Ti substrate were examined. The results of in vitro and in vivo tests and the analysis of the protein layer adsorbed to each surface were compared and discussed. In vitro analysis with MC3T3-E1 osteoblastic cells, showed that the sol-gel coating raised the osteogenic activity potential of the implants (the expression of osteogenic markers, the alkaline phosphatase (ALP) and IL-6 mRNAs, increased). In the in vivo experiments using as model rabbit tibiae, both types of surfaces promoted osseointegration. However, the coated implants demonstrated a clear increase in the inflammatory activity in comparison with SAE-Ti. Mass spectrometry (LC-MS/MS) analysis showed differences in the composition of protein layers formed on the two tested surfaces. Large quantities of apolipoproteins were found attached predominantly to SAE-Ti. The 35M35G30T coating adsorbed a significant quantity of complement proteins, which might be related to the material intrinsic bioactivity, following an associated, natural and controlled immune response. The correlation between the proteomic data and the in vitro and in vivo outcomes is discussed on this experimental work.

Proteomic analysis of silica hybrid sol-gel coatings: a potential tool for predicting the biocompatibility of implants in vivo.

The interactions of implanted biomaterials with the host organism determine the success or failure of an implantation. Normally, their biocompatibility is assessed using in vitro tests. Unfortunately, in vitro and in vivo results are not always concordant; new, effective methods of biomaterial characterisation are urgently needed to predict the in vivo outcome. As the first layer of proteins adsorbed onto the biomaterial surfaces might condition the host response, mass spectrometry analysis was performed to characterise these proteins. Four distinct hybrid sol-gel biomaterials were tested. The in vitro results were similar for all the materials examined here. However, in vivo, the materials behaved differently. Six of the 171 adsorbed proteins were significantly more abundant on the materials with weak biocompatibility; these proteins are associated with the complement pathway. Thus, protein analysis might be a suitable tool to predict the in vivo outcomes of implantations using newly formulated biomaterials.

Strongyloides stercoralis hyperinfection transmitted by liver allograft in a transplant recipient.

We describe a case of Strongyloides stercoralis hyperinfection in a liver allograft recipient 2.5 months after transplantation. The patient lives in Spain, which is not considered an endemic country for strongyloidiasis, and denied prior residence or travel to any known endemic area. The initial symptoms were fever and vomiting, and he subsequently developed a severe respiratory disease. An endoscopic biopsy of ulcerative lesions of the duodenum revealed massive mucosa infiltration by larvae and adult worms, which were also found in respiratory samples. The patient was successfully treated with combined therapy with albendazole and ivermectin. The strongyloides infection was transmitted by the liver allograft. The donor was from Ecuador and, retrospectively, his serum tested positive for S. stercoralis IgG antibodies. Additionally, the pancreas-left kidney allograft recipient from the same donor later developed an intestinal strongyloidiasis without hyperinfection syndrome. To our knowledge, this is the first confirmed case of S. stercoralis infection transmission from the same donor to two solid allograft recipients.

Correlation between the radiologic and histologic size of hepatocellular carcinoma in patients eligible for liver transplantation.

Hepatocellular carcinoma is the most prevalent primary hepatic tumor. Early diagnosis and staging is of paramount importance to obtain favorable survivals. So far, there is no general agreement on the most appropriate imaging technique to detect the tumor for correlation between pretransplant radiologic and pathologic size of the tumor, which remains inadequate. With greater clinical experience and increasing accuracy of imaging methods, magnetic resonance (MR) appears to be the most accurate method, yielding a correlation in 67% of cases.

Glutathione S-transferase T1 genetic mismatch is a risk factor for de novo immune hepatitis in liver transplantation.

Glutathione S-transferase T1 (GSTT1) is a drug metabolizing enzyme abundantly expressed in liver and kidney cells; it is encoded by a single gene that is absent in 20% of the Caucasian population. Our group found that some liver transplantation patients developed de novo immune hepatitis (IH) and that all of them had anti-GSTT1 antibodies. The main objective of this study was to analyze the influence of a GSTT1 mismatch between donor and recipient in the immune response and the outcome of the graft. We confirmed that only under one of the four possible genetic combinations (null recipient/positive donor) is an alloimmune response triggered with production of anti-GSTT1 antibodies. Therefore, we conclude that this genetic mismatch can be considered a risk factor for de novo IH.

Thermal sensitivity of growth, food intake and activity of juvenile brown trout.

Growth rate, food intake and activity of juvenile brown trout (Salmo trutta L.) were studied at 10 constant temperatures (2.6-22.3 degrees C) and using eight full-sib families. We found between-family differences in growth rate but not significant temperaturexfamily interaction. The effects of temperature were well described by polynomial regressions that allowed the calculation of optima, performance breadths and thermal limits. The obtained values were noticeably higher and the performance breadth wider, than previously reported data for the species.

[Open clinical trial with oral acyclovir for the prophylaxis of disease by Cytomegalovirus in low risk liver transplant recipients]. / Ensayo clínico abierto con aciclovir oral para la profilaxis de la enfermedad por Citomegalovirus en receptores de trasplante hepático de bajo riesgo.

OBJECTIVE: Checking the first 70 low risk liver transplantation performed in our hospital, who did not receive prophylaxis for Cytomegalovirus, we found that the incidence of Cytomegalovirus-infection and Cytomegalovirus-disease were 47% and 16% respectively. METHODS: For this reason we started a prospective, open clinical study, to address the safety of acyclovir prophylaxis in low-risk liver transplant patients. Seventy patients did not receive acyclovir. Fifty patients received oral acyclovir during 3 months (800-3,200 mg/day). RESULTS: The occurrence of Cytomegalovirus infection was not modified (40%) but Cytomegalovirus disease decreased dramatically (4%, p < 0.01) during the first year after transplantation. Acyclovir was well tolerated. The incidence of leukopenia and renal failure were similar in both groups. Acyclovir did not improved the global survival of patients. CONCLUSIONS: Thus, oral acyclovir does not reduce Cytomegalovirus infection although it is efficient and safe in the prevention of Cytomegalovirus disease in low-risk liver transplantation, and prevents Herpes-simplex and Varicela-zoster symptomatic disease in this group of patients.

[Acyclovir may modulate clonal expansion of cd8+ lymphocytes induced by the Cytomegalovirus antigen]. / El aciclovir puede modular la expansión clonal de linfocitos CD8+ inducida por antígeno de Citomegalovirus.

BACKGROUND: Although the potent antiviral effect of acyclovir on the Herpes-simplex (HSV) and Varicela-zoster (VZV) virus and the scarce effectiveness versus Cytomegalovirus (CMV) is known, some data suggest that it may have an immunodulator implicated in the control of these viral disease. The aim of this study was to characterize this possible effect of acyclovir versus the CMV antigen. METHODS: We stimulated cultures of mononuclear cells obtained in 7 healthy patients who were seropositive for CMV and HSV with CMV antigen, HSV and with phitohemaglutinine (PHA). The proliferation index and culture cell phenotype were later determined in the absence and presence of acyclovir (2 micrograms/ml). In another group the proliferation index and cell phenotype following stimulation with the CMV antigen were studied prior to and after treating the same volunteers with acyclovir for one week (800 mg/6h). RESULTS: The CMV antigen and HSV induced T cell proliferation predominantly involving the CD8+ subpopulation leading to an inversion of the CD4/CD8 quotient. On addition of acyclovir to the cell culture a moderate reduction was produced in lymphoproliferative response versus the CMV antigen and HVS, characteristically modulating CD8+ cell proliferation, thereby leading to reestablishment of the CD4/CD8 quotient. However, the proliferation induced by PHA was not inhibited. These results were produced on oral administration of acyclovir. CONCLUSIONS: Acyclovir modulates the lymphoproliferative response induced by CMV antigen. Based on this observation, the authors hypothesize that this immunomodulation may be related to its preventive effect on CMV disease in transplanted patients.

[Non-immunoallergic hepatotoxicity due to mesalazine]. / Hepatotoxicidad no inmunoalérgica por mesalazina.

Mesalazine is an aminosalicillic derivative considered as a safe alternative to the relative frequency (5-55%) of adverse effects observed with sulfasalazine. The well known hepatoxicity associated with sulfasalazine and attributed to its sulfamidic fraction is limited to few cases described in the treatment with mesalazine. We herein present a new case of hepatoxicity by mesalazine in a patient with lymphocytic colitis. The possible pathogenic mechanism is also commented upon.