ABSTRACT
We investigated the effects of citric acid (CA) on cultured human osteoblastic (HOB) cells by evaluating cell adhesion, proliferation, and cytotoxicity. (3)H-Thymidine-labeled HOB cells were incubated in culture medium supplemented or not with 4%, 6%, 8%, or 10% CA for 1 minute. After incubation, cell morphology was evaluated by Nomarski interferential light microscopy, cell proliferation was accessed by measurements of (3)H-thymidine associated to the cells, and cell lysis was monitored by measuring the amount of (3)H-thymidine released by cells. We observed that most of the CA-treated cells presented numerous atypical vacuoles, and such cells were also highly polymorphic, exhibiting round-shaped cells. Nonetheless, CA at all concentrations assayed did not yield cytotoxicity as measured by (3)H-containing DNA release, although significant decrease in cell proliferation was observed (P > .05). Furthermore, cells which were treated with CA at the lowest concentration assayed (4%) restored normal proliferation rates 3 days after treatment.
Subject(s)
Citric Acid/pharmacology , Osteoblasts/drug effects , Cell Adhesion/drug effects , Cell Culture Techniques , Cell Death/drug effects , Cell Proliferation/drug effects , Cell Shape/drug effects , Cells, Cultured , Citric Acid/toxicity , Culture Media , Humans , Hydrogen-Ion Concentration , Microscopy, Interference , Pseudopodia/drug effects , Radiopharmaceuticals , Thymidine , Time Factors , Tritium , Vacuoles/drug effectsABSTRACT
O conhecimento acumulado na última década sobre as interações mecanoquímicas entre implantes de titânio e tecidos animais revela o papel crucial desempenhado pela interface célula-matriz extracelular (MEC)-titânio na biocompatibilidade do último. Nesse contexto, e focalizando a interação células ósseas-MEC-titânio, esta breve revisão discute e apresenta alguns dados originais relativos ao comportamento de células formadoras de osso ou osteoblastos sobre superfícies de titânio, sob a intermediação de componentes da matriz extracelular. Como enfatizado em publicações recentes, o conhecimento subjacente a este tema é relevante para as modernas clínicas odontológica, médica e veterinária, assim como para empresas envolvidas no desenho e no desenvolvimento de implantes de titânio.
The accumulated knowledge during last decade on the mechanochemical interactions between titanium implants and animal tissues has point out the crucial role played by the cell-extracellular matrix (ECM)-titanium interface in the biocompatibility of the last. In this context, and specifi cally focusing the bone cells-ECM-titanium interaction relationships, this brief revision includes a discussion and some original data all concerning the behavior of bone-forming cells or osteoblasts onto titanium surfaces under the intervention of extracellular matrix components. As emphasized in recent publications, the knowledge underlying this subject is relevant for the modern dental, medical and veterinary clinics, as well as to companies involved in both design and development of titanium implants.
Subject(s)
Dental Implants , Extracellular Matrix , TitaniumABSTRACT
Acanthamoeba spp. contains a group of free-living amoebae widespread in nature. These microorganisms may cause several diseases in humans including osteomyelitis. Here we characterize the cellular interaction between clinical and freshwater isolates of A. polyphaga with human osteoblasts. Amoeba cytoadherence was evaluated quantitatively and qualitatively. We observed that the clinical isolate readily adheres to human osteoblastic cells (HOB) in a saturable and time-dependent fashion. The cytoadhesion appears to be in part dependent on mannose-associated surface glycoconjugates, since prior incubation of the amoebae with alpha-mannose reduced cytoadhesion approximately 75%. Scanning electron microscopy revealed various amoebae exhibiting acanthapodia contacting the surface of osteoblasts. Some osteoblasts developed morphologies resembling apoptotic cells. The clinical isolate was highly toxic to HOB cells during 24 h of cell-protozoan interaction. Cytotoxicity was also dependent on the amoeba-cell ratio. During the cytopathogenic process we observed amoebae in the apparent process of ingestion of target cells and also amoebae extending projections or digipodia into osteoblast targets. The results indicate that A. polyphaga trophozoites attach and destroy human osteoblasts.
