Evaluation of cell morphology and adhesion capacity of human gingival fibroblasts on titanium discs with different roughened surfaces: an in vitro scanning electron microscope analysis and cell culture study

BACKGROUND

Implantoplasty is an option in peri-implantitis treatment. What is known about the effects of implantoplasty on peri-implant soft tissue adhesion and cell behaviours is limited. This study aimed to evaluate the morphological features and adhesion capacity of human gingival fibroblast (HGF) cells onto sand-blasted, large-grit, acid-etched (SLA®) titanium (Ti) discs surfaces roughened with different implantoplasty protocols.

MATERIALS AND METHODS

The study included a total of 48 Ti discs divided into four groups (n = 12 per group): Group I: machined, smooth surface discs; Group II: SLA® surface discs; Group III: SLA® surface discs roughened with diamond bur sequence (40 and 15-μm grit); Group IV: SLA® surface discs roughened with diamond bur sequence (125 and 40-μm grit). Following polishing procedure, the surface roughness value of discs was assessed by a profilometer and scanning electron microscope. HGFs were cultured on Ti discs and cell adhesion was examined after the 24th, 48th, and 72nd hours. Statistical significance was set at the p ≤ 0.05 level.

RESULTS

Scanning electron microscope analyses of the discs revealed that fibroblasts exhibited well-dispersion and a firm attachment in all groups. The cells in group I and II had thin and long radial extensions from the areas where the nucleus was located to the periphery; however, attached cells in group III and IV showed more spindle-shaped morphology. The surface roughness parameters of the test groups were lower than those of the SLA®. The SLA® group showed the highest HGF adhesion (group II) (p ≤ 0.05). HGF adhesion in group IV was greater compared to group III, but less than group I.

CONCLUSIONS

This study showed that the characteristics of the burs applied in the implantoplasty protocol are determinant for the surface roughness and fibroblast adhesion occurs on surfaces with decreased roughness following implantoplasty. Consequently, it should be kept in mind that the surface properties of the implant may affect the adherent cell morphology and adhesion.

206 COMPARATIVE EVALUATION OF VARIOUS PROTOCOLS FOR NEURAL DIFFERENTIATION OF MOUSE EMBRYONIC STEM CELLS

Mouse embryonic stem (ES) cells derived from the inner cell mass of blastocysts can differentiate into neuronal cells by treatment with retinoic acid (RA). ES cells cultured as aggregates and as single cell suspensions were then exposed to RA which induced multiple phenotypes of neuronal cells. Differentiation was dependent on the concentration of RA and the time of exposure. In this study, we cultured ES cells as a suspension in which they formed embryoid bodies (EBs). The EBs were treated with varying concentrations of RA for differing times. We used increasing concentrations of RA (50 nM, 100 nM, 1 �M, and 3 �M) prepared from a stock of 10 mM RA in DMSO. Immunocytochemistry staining was carried out on 2, 5, 7, and 9 days of culture. We formed EBs for 4 days with standard ES cell medium (without LIF) plus an additional 4 days of treatment with 1 �M RA. ES cells were treated with 1 �M RA for 2 days in suspension culture. Two-day-old EBs plated on culture dishes were treated with 1 �M RA for 3 days. To test for the effect of RA concentration on embryonic differentiation, 2-day-old EBs were treated with 50 nM, 100 nM, 1 �M, and 3 �M RA for 3 days. The time-dependent effects of RA on the 4-/4+ RA group were investigated. Results showed that neuronal precursor cells appeared on the second day of culture; they were stained with nestin antibody. On the 5th day of culture, neurons were detected with NCAM antibody. On the 7th day of culture, glial cells were observed with GFAP, and on the 9th day of culture GFAP, expression increased. In EBs that were plated and then treated with RA, the same results were obtained. RA induced neuronal differentiation in a concentration-dependent manner. Low concentrations (50 nM and 100 nM) of RA induced neuronal differentiation besides mesenchymal differentiation; however, higher concentrations (1 �M and 3 �M) of RA did not induce mesenchymal differentiation. The most efficient neuronal differentiation was obtained at 3 mM RA concentration. This study was performed in TUBITAK Research Institute for Genetic Engineering and biotechnology.

The effects of ovulation induction on ovarian epithelium dysplasia scores and Ki67 expression: an experimental study on rats

We aimed to evaluate the effects of ovulation induction on Ki67 expression and dysplasia scores of female rat ovaries. Twenty female Wistar rats were randomized either to receive 150 IU/kg human menopausal gonadotropin on estrous day 2 and 75 IU/kg human chorionic gonadotropin on the day of preestrous (induction group, n= 10) or saline as placebo on the corresponding days (control group, n= 10). After five estrous cycles bilateral oophorectomy was performed to compare the Ki67 expression and dysplasia score of the ovarian epithelium. The mean number of the cells that stained positive for Ki67 was 159.6 +/- 101.92 in the follicles, 283.4 +/- 42 in the corpus luteum, and 151 +/- 75.1 in the stroma of the study group compared to 41.8 +/- 35.6 (P= 0.03), 43.2 +/- 28.3 (P= 0.007), and 55.6 +/- 18.6 (P= 0.01), respectively, in the control group. The mean number and rate of cells that stained positive for Ki67 in the epithelium was significantly higher in the ovulation induction group (758 +/- 71 and 63 +/- 1.6%, respectively) compared to the control group (386 +/- 23, P < 0.001; and 60 +/- 1.1%, P < 0.001; respectively). The mean dysplasia score was significantly higher (9.6 +/- 1.3) in the study group compared to the control group (5.08 +/- 0.9, P < 0.001). Ovulation induction in rats resulted in increased Ki67 expression and dysplastic features in the ovarian epithelial cells.

Effect of insulin-like growth factor-1 on apoptosis of rat testicular germ cells induced by testicular torsion

OBJECTIVE

To investigate the possible protective role of insulin-like growth factor-1 (IGF-1, reported to have a protective effect in experimental models of hypoxic ischaemia), and the involvement of apoptotic cell death in a model of torsion/detorsion of the rat testis.

MATERIALS AND METHODS

Adult male Wistar rats were divided into five groups of five rats each. Group 1 underwent a sham operation as a control; in group 2 the testis was twisted and in group 3 then untwisted; in group 4 IGF-1 was injected subcutaneously just before bilateral torsion, and then the right testis removed after 4 h and the left after 24 h; in group 5, IGF-1 was injected immediately after bilateral detorsion and then the testes removed as in group 4. Both testicles were examined histologically, with apoptosis detected using the in situ DNA fragmentation (TUNEL) system, with combined enzymology and immunohistochemistry techniques.

RESULTS

In groups 2 (torsion) and 3 (detorsion), light microscopy of the testis showed some degenerative changes in the germ cells. Compared to group 1, apoptosis was more significant in group 3 than in the other groups. Group 4 (torsion/IGF-1) had a similar number of apoptotic germ cells as in group 2 (torsion) after 24 h, but fewer than the same group after 4 h. In group 5 (detorsion/IGF-1), apoptosis was reduced by IGF-1 significantly more than in group 3 (P < 0.05). Apoptosis was significantly less in spermatids in group 5 than in group 3 (P < 0.05).

CONCLUSIONS

IGF-1 seems to lower the levels of germ cell apoptosis, which may be important for protecting the testes from torsion/detorsion injury. Further clinical studies are needed to evaluate this protective effect in testicular torsion/detorsion.

Localization of neural cell adhesion molecule (N-CAM) immunoreactivity in adult rat tissues

Neural cell adhesion molecule (N-CAM) mediates homophilic adhesion between cells and heterophilic adhesion between cells and extracellular matrix in a Ca2+-independent manner. N-CAM is widely expressed during development and plays a crucial role in cell division, migration, and differentiation, but its expression is restricted in adults. The distribution of N-CAM immunoreactivity in adult rat tissues was investigated in the present study. N-CAM immunoreactivity was present in the nervous system in the molecular layer of the cerebellum, ependymal cells surrounding the central canal, axons of the white matter, and in Lamina X of the gray matter of the spinal cord. N-CAM immunoreactivity also was found in autonomic nerves. In the digestive system, N-CAM immunoreactivity was found in the stratified squamous epithelium and nerve plexus of the esophagus, glandular cells of the stomach and pylorus, lamina propria, and epithelium of the villi of the duodenum, jejunum, and ileum. N-CAM immunoreactivity was demonstrated in the secretory cells of the adenohypophysis, islets of Langerhans, and acinar cells of the exocrine pancreas. Alveolar cells of the lung were also N-CAM immunoreactive. In the urinary system, N-CAM immunoreactivity was seen in the proximal convoluted tubules of the kidney. In the male reproductive system, N-CAM immunoreactivity was demonstrated in the nerve plexus around the urethral epithelium and in the nerve fibers around the smooth muscle cells of the corpus cavernosum penis. In the visual system, N-CAM immunoreactivity was seen in the epithelial cells of the corpus ciliaris. Cornea and lens epithelium also showed positive immunoreactivity. Our results suggest that cells in many tissues and organs of the adult rat synthesize N-CAM.

The cellular localization of vasoactive intestinal peptide (VIP) in the mouse median eminence by immuno-electron microscopy

The aim of this study was to examine, by use of pre-embedding immunocytochemistry, the ultrastructural localization of vasoactive intestinal peptide (VIP) immunoreactivity in the mouse median eminence. VIP immunoreactivity was observed in axonal profiles. The VIP-immunoreactive axonal profiles were in close proximity to non-immunoreactive axonal profiles that contained dense granular vesicles and clear vesicles and also to processes of tanycytes. VIP-immunoreactive terminals were observed in the proximity of the perivascular space and in the neuropil. Our results suggest that VIP-immunoreactive axon terminals may possibly interact with other non-immunoreactive axon terminals containing peptide and/or other transmitters at the level of the median eminence or may be released to the portal vasculature thereby to effect anterior pituitary cells.

Growth hormone-releasing hormone peptide and mRNA are overexpressed in GH-deficient Ames dwarf mice

Hypothalamic expression of growth hormone-releasing hormone (GHRH) was quantified morphologically in dwarf mice which exhibit spontaneous genetic GH absence. Mouse GHRH mRNA was assessed by in situ hybridization; densitometric evaluation of total mRNA in dwarfs showed levels 2.3-fold higher than in phenotypically normal siblings (p < 0.01); assessment of mRNA per neuron by autoradiographic grain counting indicated a 2.5-fold increase per cell in dwarfs (p < 0.005). GHRH peptide was evaluated immunocytochemically using a new mouse-specific antiserum; numbers of neurons containing detectable levels were 3-fold higher in dwarfs (p < 0.005). The increase in GHRH mRNA corroborates that reported previously in the GH-deficient little mouse, and after hypophysectomy in rats; GHRH peptide increase contrasts with previous reports of the effect of acute GH removal by hypophysectomy, in which GHRH levels fell. The results suggest that chronic GH deficiency is accompanied by increased translation as well as transcription of GHRH.

Median eminence-afferent vasoactive intestinal peptide (VIP) neurons in the hypothalamus: localization by simultaneous tract tracing and immunocytochemistry

Retrograde tract tracing and immunocytochemistry were used to investigate the CNS source of the VIP that is present in high concentrations in the hypophysial portal blood and has been shown to have a stimulatory effect on pituitary prolactin secretion. Fluoro-gold (FG), which enters the CNS through areas devoid of the blood-brain barrier, such as median eminence, was injected peripherally. Brain sections from FG-treated animals were immunostained for VIP. A small population of VIP-containing cell bodies in the parvocellular and periventricular parts of the paraventricular nucleus (PVN) was also labeled with FG. Vasoactive intestinal peptide-immunoreactive perikarya not labeled with FG were also observed in the PVN, as well as FG-labeled cells that did not contain VIP. The results suggest that some VIP-producing neurons in the PVN project to the median eminence and are, therefore, functionally related to pituitary regulation; the function of other VIP neurons in the PVN is unknown.