A 635-nm light-emitting diode (LED) therapy inhibits bone resorptive osteoclast formation by regulating the actin cytoskeleton.

Bone diseases such as osteoporosis are mainly caused by upregulated activity of osteoclasts. The present study was designed to examine the effects of light-emitting diode (LED) irradiation on the formation and activity of multinucleated osteoclasts, specifically "round-shaped" osteoclast cells (ROC) in different cell types derived from mouse. After 635-nm LED irradiation, the cell viability was evaluated by MTT assay. The amount of total tartrate-resistant acid phosphatase (TRAP) + osteoclast and the number of ROC cells were also estimated by TRAP solution assay and TRAP staining, respectively. Actin rings were stained with rhodamine-conjugated phalloidin, and resorption assay was performed by dentin slices. In addition, gene expression levels between the control and irradiation groups were evaluated by RT-PCR. In a morphological analysis, the formation of ROC was significantly inhibited by 635-nm LED irradiation in the different cell types. Actin rings were seen at cell peripheries in most ROC cells of the control group, but patches containing disorganized actin were found in the irradiation group. Both the number of ROCs and bone resorption activity were much lower in the irradiation group than in the control group. Also, the gene expression levels involved in actin ring formation such as integrin ß3 and c-Src decreased in RT-PCR analysis. Overall, 635-nm LED therapy may play a pivotal role in regulating bone remodeling, and it may prove to be a valuable tool to prevent bone loss in osteoporosis and other resorptive bone diseases.

[Induction of micronuclei in peripheral blood and bone marrow reticulocytes of male mice after subchronic exposure to x-rays and bisphenol A]. / Indukcja mikrojader w krwi obwodowej i szpiku kostnym samców myszy narazanych subchronicznie na dzialanie promieniowania x i bisfenolu A.

BACKGROUND: Ionizing radiation and xenoestrogens are widely present in the human environment. Bisphenol A (BPA) is used to manufacture polycarbonate plastics, epoxy and polyester resins. BPA is present in a great variety of products including: baby bottles, compact disks, thermal paper, safety helmets, bullet resistant laminate, plastic windows, car parts, adhesives, protective coatings, powder paints, polycarbonate bottles and containers, the sheathing of electrical and electronic parts, dental fillings. Food and beverage cans are protected from rusting and corrosion by the application of epoxy resins as inner coatings. Human activities involving the use of radiation and radioactive materials in industry, agriculture and research cause radiation exposure in addition to natural exposure coming from cosmic rays and naturally occurring radioactive substances. OBJECTIVE: The aim of the study was to estimate the effects of bisphenol A, X-rays and combined exposure to X-rays and bisphenol A on the induction of micronuclei in the peripheral blood and in bone marrow reticulocytes of laboratory mice. MATERIAL AND METHOD: Pzh-Sfis male mice were exposed for 8 weeks. Animals were treated with bisphenol A diluted in drinking water (5 mg/kg bw, 10 mg/kg bw, 20 mg/kg bw), irradiated 0.05 Gy of X-rays or exposed to a combination of both (0.05 Gy + 5 mg/kg bw BPA). The samples of peripheral blood were taken at 1, 4 and 8 week following the start of exposure, whereas the bone marrow after the end of experiment, only. The induction of micronuclei in reticulocytes were evaluated by using fluorescence microscope. RESULTS: Bisphenol A as well as ionizing radiation stimulated induction of micronuclei in peripheral blood and bone marrow reticulocytes. After the irradiation the level of micronuclei increased, whereas after exposure to BPA decreased related to time expired from beginning of experiment. Combined exposure of ionizing radiation and bisphenol A induced significantly higher frequency of micronuclei compared to the effect produced by BPA alone. The frequency of micronuclei in peripheral blood reticulocytes increased during the experiment. In all groups, the significantly lower induction ofmicronuclei in reticulocytes of bone marrow than of peripheral blood were observed. The levels ofmicronuclei in mice exposed to a combination of X-rays and BPA or to irradiation alone were slightly higher compared to those administered to BPA alone. CONCLUSIONS: Bisphenol A induced micronuclei in peripheral blood and bone marrow reticulocytes. Subchronic BPA exposure leads to diminished sensitivity of genetic material of reticulocytes on the induction of damage. X-rays is probably the agent which decided about DNA damage following combined exposure.

Assessment of electromechanically stimulated bone marrow stem cells seeded acellular cardiac patch in a rat myocardial infarct model.

In this study, we evaluated cardiomyogenic differentiation of electromechanically stimulated rat bone marrow-derived stem cells (rt-BMSCs) on an acellular bovine pericardium (aBP) and we looked at the functioning of this engineered patch in a rat myocardial infarct (MI) model. aBP was prepared using a detergent-based decellularization procedure followed by rt-BMSCs seeding, and electrical, mechanical, or electromechanical stimulations (3 millisecond pulses of 5 V cm-1at 1 Hz, 5% stretching) to enhance cardiomyogenic differentiation. Furthermore, the electromechanically stimulated patch was applied to the MI region over 3 weeks. After this period, the retrieved patch and infarct region were evaluated for the presence of calcification, inflammatory reaction (CD68), patch to host tissue cell migration, and structural sarcomere protein expressions. In conjunction with any sign of calcification, a higher number of BrdU-labelled cells, and a low level of CD68 positive cells were observed in the infarct region under electromechanically stimulated conditions compared with static conditions. More importantly, MHC, SAC, Troponin T, and N-cad positive cells were observed in both infarct region, and retrieved engineered patch after 3 weeks. In a clear alignment with other results, our developed acellular patch promoted the expression of cardiomyogenic differentiation factors under electromechanical stimulation. Our engineered patch showed a successful integration with the host tissue followed by the cell migration to the infarct region.

3D­printed Ti6Al4V scaffolds combined with pulse electromagnetic fields enhance osseointegration in osteoporosis.

The loosening and displacement of prostheses after dental implantation and arthroplasty is a substantial medical burden due to the complex correction surgery. Three­dimensional (3D)­printed porous titanium (pTi) alloy scaffolds are characterized by low stiffness, are beneficial to bone ingrowth, and may be used in orthopedic applications. However, for the bio­inert nature between host bone and implants, titanium alloy remains poorly compatible with osseointegration, especially in disease conditions, such as osteoporosis. In the present study, 3D­printed pTi scaffolds with ideal pore size and porosity matching the bone tissue, were combined with pulse electromagnetic fields (PEMF), an exogenous osteogenic induction stimulation, to evaluate osseointegration in osteoporosis. In vitro, external PEMF significantly improved osteoporosis­derived bone marrow mesenchymal stem cell proliferation and osteogenic differentiation on the surface of pTi scaffolds by enhancing the expression of alkaline phosphatase, runt­related transcription factor­2, osteocalcin, and bone morphogenetic protein­2. In vivo, Microcomputed tomography analysis and histological evaluation indicated the external PEMF markedly enhanced bone regeneration and osseointegration. This novel therapeutic strategy has potential to promote osseointegration of dental implants or artificial prostheses for patients with osteoporosis.

[Use of perfluorocarbon emulsions for administration of photosensitizing preparations into bone marrow stem cells].

It has been shown that, upon incubation of mouse bone marrow stem cells (BMSC) in vitro with the nanoparticles of perfluorocarbon (PFC) emulsion stabilized by proxanol 268, these nanoparticles penetrate into cells and stay there for a long time (up to 20 days of observation). It has been found that, under in vitro conditions, mouse BMSC loaded with the nanoparticles of both the original emulsion and the emulsion preliminarily incubated with radachlorine do not differ from control stem cells in the rate of division, stretching on a plastic support, and the formation of a monolayer. It has been shown that the exposure to laser radiation of BMSC incubated with the nanoparticles of a PFC emulsion preliminarily incubated with radachlorine under in vitro conditions leads to the death of these cells due to the destruction of the cell membrane. The treatment with laser radiation of BMSC incubated with the nanoparticles of the starting PFC emulsion (without preliminarily incubation with radachlorine) causes no death of these cells. It has been shown in in vivo experiments that, when transplanted to the organism of a recipient mouse, BMSC of a donor mouse incubated with the nanoparticles of a PFC emulsion preliminarily incubated with radachlorine retain their functional activity, in particular the ability to migrate in the animal body. In this case, radachlorine contained in these stem cells retains its major function, to induce the death of stem cells by the action of laser radiation due to the destruction of the cell membrane. The observation period after the transplantation was 5-7 days.

Pluronic-F127/Platelet Microvesicles nanocomplex delivers stem cells in high doses to the bone marrow and confers post-irradiation survival.

Platelet microvesicles (pMVs) are submicron-sized heterogeneous vesicles released upon activation and contain several membrane receptors and proteins (CD41, CD61, CD62, CXCR4, PAR-1, etc.). We have revealed their ability to adhere to the triblock copolymer pluronic-F127 (PF127) and form a platelet microvesicular nanocloud which has the potential to enhance the transvascular migration of hematopoietic stem cells across the sinusoidal endothelium to the bone marrow. Besides, the pMVs nanoclouds bestow survival benefits when present on the cells used for infusion, particularly with PF127-stabilized with chitosan-alginate (PF127-CA HSCs). The vesicles were found to be firmly associated with PF127 in the nanocloud, which was detected by confocal laser scanning microscopy. The abrogation of CXCR4/SDF-1 axis regulating the transmigration of the cells by antagonist AMD3100 revealed that the enriched CXCR4 receptors on pMVs robustize the transmigration of the infused cells. The homing of the cells led to effective engraftment and faster regeneration of the critical blood lineages, which elicited 100% survival of the mice receiving lethal doses of radiation. The Human Long-Term Culture Initiating Cells (LTC-ICs), Severe Combined Immunodeficient (SCID) - Repopulating Cells (SRCs) and Colony Forming Cells (CFCs) responsible for the regeneration, but present in extremely low numbers in the infused cell dose, have enabled the cells to reach the bone marrow in high numbers. This potential of the PF127 to sequester the pMVs and its application to achieve over 10-fold delivery of HSCs across the trans-endothelial checkpoint has so far not been reported. Thus, this mechanistic innovation is a potential post-exposure life-saving regimen capable of circumventing the irreparable damage to the bone marrow caused by lethal doses of radiation.

Effect of several sterilisation techniques on homogeneous self assembled monolayers.

Understanding how cells sense their environment and are able to regulate their metabolism is of great importance for the success of biomaterials implantation. Self assembled monolayers (SAMs) are in use nowadays to model the surface of such materials. They permit the control of different surface parameters (like chemistry, surface energy and topography) enabling to get a greater insight in cells behaviour when interacting with surfaces and thus, in the future, to enhance surface properties of biomaterials. As sterilisation is the compulsory step for in vitro and in vivo assays with living biological materials, it is important to know how SAMs react under sterilisation techniques in use on biomaterials. In this work, the effect of three types of sterilisation techniques: gamma-irradiation, mostly used on biomaterials, dry heat and steam autoclaving, have been investigated on NH2 and CH3 terminated SAMs. Gamma-irradiation destructs drastically the NH2 and partially the CH3 monolayers by producing oxidative compounds (COOH, C=O, C-OH). The main product induced by gamma-irradiation on NH2 monolayers is carboxylic acid, whereas CH3 shows an important increase in the amount of alcoholic groups. This difference in deterioration is assumed to be due to the higher stability of the CH3 monolayer. Steam autoclaving to a lesser extent gives the same results on NH2 monolayers. Dry heat seems to be the most reliable technique, which can be used on such surfaces as it removes physically adsorbed organic contaminants without affecting the integrity of the surface.

A schedule of recombinant Mpl ligand highly effective at preventing lethal myelosuppression in mice given carboplatin and radiation.

OBJECTIVE: To determine a thrombopoietin schedule that would effectively enhance hematopoiesis and prevent death in mice after lethal myelosuppression. METHODS: First, we determined whether recombinant Mpl ligand (Mpl-L) has a priming effect on thrombopoiesis in normal mice. Mice were given pegylated recombinant murine Megakaryocyte Growth and Development Factor (PEG-rmMGDF) intravenously as a single injection or as two injections separated by intervals of 1 to 10 days. Second, we examined the scheduling of PEG-rmMGDF that would most effectively reduce thrombocytopenia in mice given a lethal myelosuppressive regimen (80 mg/kg carboplatin + 750 R Cs-137 total-body irradiation). RESULTS: In normal mice, peak platelet count with a 4-day to 8-day interval between PEG-rmMGDF injections was significantly higher than that with single injection. This priming effect was optimal with a 4-day interval between injections. In the lethal myelosuppression model, all mice given intravenous PEG-rmMGDF as a single injection on day 0 or as two injections (on days -4 and 0 or on days 0 and 4) survived; PEG-rmMGDF on day 0 was given immediately after the myelosuppressive regimen. In contrast, all mice given a single intravenous PEG-rmMGDF injection on day -4 or day 4 died. Two PEG-rmMGDF injections given on days -4 and 0 enhanced hematopoietic recovery more than did a single injection on day 0 or two injections on days 0 and 4. CONCLUSION: Mpl-L administration immediately after lethal carboplatin and radiation prevents death and enhances hematopoietic recovery in mice; this protective effect is further enhanced by a priming Mpl-L dose given 4 days before the myelosuppressive regimen.

Interferon alpha reduces the level of radiation-induced micronuclei in mouse bone marrow cells.

The effect of natural mouse interferon alpha (IFN-alpha) on production of micronuclei (MN) in bone marrow cells of whole-body gamma-irradiated mice (in sublethal dose of 0.5 Gy from 60Co source) was studied. It was shown that free interferon alpha (IFN-alpha(F)) and IFN-alpha encapsulated into liposomes (IFN-alpha(L)), when injected intraperitoneally to mice prior to their irradiation, reduced substantially the frequency of gamma-ray-induced micronuclei in polychromatic erythrocytes (MN-PCE) of the bone marrow of these mice. The antimutagenic effect of IFN-alpha(F), as registered by the micronucleus test, was observed in bone marrow cells of mice irradiated 24 h after injection. For IFN-alpha(L), the decrease in MN frequency in PCE of mice was observed 48-72 h after administration of the preparation.

Simultaneous interaction of bacteria and tissue cells with photocatalytically activated, anodized titanium surfaces.

Photocatalytic-activation of anodized TiO2-surfaces has been demonstrated to yield antibacterial and tissue integrating effects, but effects on simultaneous growth of tissue cells and bacteria in co-culture have never been studied. Moreover, it is unknown how human-bone-marrow-mesenchymal-stem (hBMMS) cells, laying the groundwork for integration of titanium implants in bone, respond to photocatalytic activation of anodized TiO2-surfaces. Photocatalytically-activated, anodized titanium and titanium-alloy surfaces achieved 99.99% killing of adhering Staphylococcus epidermidis and Staphylococcus aureus, an effect that lasted for 30 days of storage in air. Surface coverage by osteoblasts was not affected by photocatalytic activation of anodized TiO2-surfaces. Co-cultures of osteoblasts with contaminating S. epidermidis however, enhanced surface coverage on photocatalytically-activated, anodized titanium-alloy surfaces. hBMMS cells grew less on photocatalytically-activated, anodized titanium surfaces, while not at all on photocatalytically-activated, anodized titanium-alloy surfaces and did not survive the presence of contaminating staphylococci. This reduced surface coverage by hBMMS cells disappeared when photocatalytically-activated, anodized titanium-alloy surfaces were exposed to buffer for 60 min, both in absence or presence of contaminating S. aureus. Consequently, it is concluded that photocatalytically-activated, anodized titanium and titanium-alloy surfaces will effectively kill peri-operatively introduced staphylococci contaminating an implant surface and constitute an effective means for antibiotic prophylaxis in cementless fixation of orthopaedic hardware.

The effect of photosensitizer drugs and light stimulation on osteoblast growth.

OBJECTIVE: A promising new treatment in dentistry involves the photodynamic process, which utilizes a combination of two therapeutic agents, namely a photosensitizer drug and a low dose of visible light. We investigated the in vitro effect of low intensity laser irradiation (visible light irradiation at 670 nm) using doses ranging between 0.5 and 3 J/cm(2), combined with nanoemulsion (NE) of the photosensitizer drug aluminum phthalocyanine chloride (AlClPc), ranging from 0.5 to 5 µmol/L, on the growth and differentiation of osteoblastic cells isolated from rat bone marrow. BACKGROUND DATA: Treatments using laser radiation of low intensity in dentistry are of great interest, especially in bucco-maxillofacial surgery and dental implantology, where this approach is currently employed to stimulate osteogenesis. In the presence of oxygen, the combination of these agents could induce cellular biostimulation, via an efficient noninvasive method. METHODS: We have done the colorimetric MTT assay, collagen content, total protein content, ALP activity and bone-like nodule formation. RESULTS: We observed that an increased number of viable cells was evident upon application of a laser dosage equal to 0.5 J/cm(2) when combined with 0.5 µmol/L of AlClPc/NE, suggesting cellular biostimulation. CONCLUSIONS: It was possible to demonstrate that low intensity laser irradiation can play an important role in promoting biostimulation of osteoblast cell cultures. Therefore, whether biostimulation of osteoblastic cell cultures by photodynamic therapy or the cytotoxic effect of this therapy occurs only depends upon the light dose, and the results can be completely reversed.

Intraesophageal manganese superoxide dismutase-plasmid liposomes ameliorates novel total-body and thoracic radiation sensitivity of NOS1-/- mice.

The effect of deletion of the nitric oxide synthase 1 gene (NOS1(-/-)) on radiosensitivity was determined. In vitro, long-term cultures of bone marrow stromal cells derived from NOS1(-/-) were more radioresistant than cells from C57BL/6NHsd (wild-type), NOS2(-/-) or NOS3(-/-) mice. Mice from each strain received 20 Gy thoracic irradiation or 9.5 Gy total-body irradiation (TBI), and NOS1(-/-) mice were more sensitive to both. To determine the etiology of radiosensitivity, studies of histopathology, lower esophageal contractility, gastrointestinal transit, blood counts, electrolytes and inflammatory markers were performed; no significant differences between irradiated NOS1(-/-) and control mice were found. Video camera surveillance revealed the cause of death in NOS1(-/-) mice to be grand mal seizures; control mice died with fatigue and listlessness associated with low blood counts after TBI. NOS1(-/-) mice were not sensitive to brain-only irradiation. MnSOD-PL therapy delivered to the esophagus of wild-type and NOS1(-/-) mice resulted in equivalent biochemical levels in both; however, in NOS1(-/-) mice, MnSOD-PL significantly increased survival after both thoracic and total-body irradiation. The mechanism of radiosensitivity of NOS1(-/-) mice and its reversal by MnSOD-PL may be related to the developmental esophageal enteric neuronal innervation abnormalities described in these mice.

Human bone marrow stromal cells display variable anatomic site-dependent response and recovery from irradiation.

OBJECTIVES: Orofacial bone is commonly affected by osteoradionecrosis (ORN) during head and neck cancer radiotherapy possibly due to interactions of several factors including radiation damage to resident bone marrow stromal cells (BMSCs). Irradiation causes DNA damage, triggers p53-dependent signalling resulting in either cell-cycle arrest or apoptosis. In same individuals, disproportionately higher rapid growth of orofacial BMSCs relative to those of axial/appendicular bones suggests their response to radiation is skeletally site-specific. We hypothesised that survival and osteogenic recovery capacity of irradiated human BMSCs is site-dependent based on anatomic skeletal site of origin. METHODS: Early passage BMSCs from maxilla, mandible and iliac crest of four normal volunteers were exposed to 2.5 to 10 Gy gamma radiation to evaluate clonogenic survival, effects on cell cycle, DNA damage, p53-related response and in vivo osteogenic regenerative capacity. RESULTS: Orofacial bone marrow stromal cells (OF-MSCs) survived higher radiation doses and recovered quicker than iliac crest (IC-MSCs) based on clonogenic survival, proliferation and accumulation in G0G1 phase. Post-irradiation p53 level was relatively unchanged but expression of p21, a downstream effector was moderately increased in OF-MSCs. Re-establishment of in vivo bone regeneration was delayed more in irradiated IC-MSCs relative to OF-MSCs. CONCLUSIONS: Effect of irradiation on human BMSCs was skeletal site-specific with OF-MSCs displaying higher radio-resistance and quicker recovery than IC-MSCs.

Evaluation of an injectable, photopolymerizable, and three-dimensional scaffold based on methacrylate-endcapped poly(D,L-lactide-co-epsilon-caprolactone) combined with autologous mesenchymal stem cells in a goat tibial unicortical defect model.

An in situ crosslinkable, biodegradable, methacrylate-endcapped poly(D,L-lactide-co-epsilon-caprolactone) in which crosslinkage is achieved by photoinitiators was developed for bone tissue regeneration. Different combinations of the polymer with bone marrow-derived mesenchymal stem cells (BMSCs) and alpha-tricalcium phosphate (alpha-TCP) were tested in a unicortical tibial defect model in eight goats. The polymers were randomly applied in one of three defects (6.0 mm diameter) using a fourth unfilled defect as control. Biocompatibility and bone-healing characteristics were evaluated by serial radiographies, histology, histomorphometry, and immunohistochemistry. The results demonstrated cell survival and proliferation in the polymer-substituted bone defects. The addition of alpha-TCP was associated with less expansion and growth of the BMSCs than other polymer composites.

The effect of UV-photofunctionalization on the time-related bioactivity of titanium and chromium-cobalt alloys.

This study examined the possible changes in the bioactivity of titanium surfaces during their aging and investigated the effect of ultraviolet (UV) light treatment during the age-related change of titanium bioactivity. Rat bone marrow-derived osteoblastic cells were cultured on new titanium disks (immediately after either acid-etching, machining, or sandblasting), 4-week-old disks (stored after processing for 4 weeks in dark ambient conditions), and 4-week-old disks treated with UVA (peak wavelength of 365 nm) or UVC (peak wavelength of 250 nm). During incubation for 24 h, only 50% of the cells were attached to the 4-week-old surfaces as compared to the new surface. UVC treatment of the aged surface increased its cell attachment capacity to a level 50% higher than the new surfaces, whereas UVA treatment had no effect. Proliferation, alkaline phosphatase activity, and mineralization of cells were substantially lower on the 4-week-old surfaces than on the new surfaces, while they were higher on the UVC-treated 4-week-old surfaces as compared to the new surfaces. The age-related impaired bioactivity was found on all titanium topographies as well as on a chromium-cobalt alloy, and was associated with an increased percentage of surface carbon. Although both UVA and UVC treatment converted the 4-week-old titanium surfaces from hydrophobic to superhydrophilic, only UVC treatment effectively reduced the surface carbon to a level equivalent to the new surface. Thus, this study uncovered a time-dependent biological degradation of titanium and chromium-cobalt alloy, and its restoration enabled by UVC phototreatment, which surmounts the innate bioactivity of new surfaces, which is more closely linked to hydrocarbon removal than the induced superhydrophilicity.

Osteoclast activation and recruitment after application of orthodontic force.

In this study, whole body radioactive cobalt 60 (Co60) irradiation was used in an orthodontic tooth movement model to investigate osteoclast activation and recruitment in adult rats. Seventy-five rats were divided into three groups and were irradiated with Co60 ranging from 10 to 26 Gray. An orthodontic appliance was fitted to each rat 12 days after initiation of irradiation. Identical appliances were fitted on an additional 25 unirradiated rats. Groups of rats were sacrificed 1 week before and on the day of appliance placement as well as 1, 2, 3, 4, or 5 weeks after appliance placement. Histologic sections from decalcified maxillary processes were prepared and osteoclasts were counted. Results showed that regardless of irradiation dosage, osteoclast number did not decrease during the first 3 weeks of orthodontic treatment; animals receiving lower (ie, 10 Gray) total irradiation actually showed a transient increase in the osteoclast number. In addition, regardless of dose in the irradiated rats, the total time osteoclasts were present in the periodontal membrane after orthodontic activation was reduced from 4 to 3 weeks. These findings lead us to hypothesize that osteoclasts involved in appliance-induced remodeling are initially from precursors in the periodontal membrane. During prolonged periods of orthodontic force application, replacement osteoclasts originate from bone marrow precursors. Although an orthodontic bone resorption cycle lasts 4 weeks, the life span of individual osteoclasts is limited to 9 to 10 days. The clinical significance of this finding remains to be elucidated.

Biostimulation of bone marrow cells with a diode soft laser.

In recent years, the use of low-intensity red light in regeneration of soft tissue has been increasingly pursued. As far as hard tissue is concerned, the biostimulating effect of laser has already been demonstrated successfully in more rapid healing of tibial bone fractures in mice at a dosage of 2.4 J. However, the effect of light of a low dose laser directly on osteoblasts has not been investigated yet. The aim of this study was to determine the effect of continuous wave diode laser irradiation on osteoblasts derived mesenchymal cells. Three groups of 10 cultures each were irradiated 3 times (days 3, 5, 7) with a pulsed diode soft laser with a wavelength of 690 nm for 60 s. Another 3 groups of 10 cultures each were used as control groups. A newly developed method employing the fluorescent antibiotic tetracycline was used to compare bone growth on these culture substrates after a period of 8, 12 and 16 days, respectively. It was found that all lased cultures demonstrated significantly more fluorescent bone deposits than the non-lased cultures. The difference was significant, as tested by the Tukey Test (P < 0.0001) in the cultures examined after 16 days. Hence it is concluded that irradiation with a pulsed diode soft laser has a biostimulating effect on osteoblasts in vitro, which might be used in osseointegration of dental implants.

Acute radiation disease and biological dosimetry in 1993.

Mankind is at risk for accidental exposure to ionizing radiation. The experience in evaluating and treating victims of radiation exposure is briefly reviewed based upon accidents occurring over the past 25 years. Individual cases of acute toxicities to the skin, gastrointestinal tract, liver and bone marrow are presented. Biodosimetry (utilizing chromosome analysis of peripheral blood lymphocytes and bone marrow and electron spin resonance spectrometry of dental enamel) has been utilized in radiation accidents to assess individual dose. Variability in the dose of ionizing radiation received is typical among the population affected by the Chernobyl accident. Whereas the acute radiation syndrome resulting in a high mortality has been well-documented, little information is available regarding the effects of chronic, low-level exposure from the Chernobyl accident.

A single dose of pegylated leridistim significantly improves neutrophil recovery in sublethally irradiated rhesus macaques.

Leridistim, a member of the myelopoietin family of dual receptor agonists that binds interleukin-3 and G-CSF receptors, has been shown to enhance hematopoietic activity in rhesus monkeys above that observed with either cytokine alone or in combination. This study demonstrated the ability of a pegylated form of leridistim (peg-leridistim), administered s.c., as a single- or two-dose regimen separated by 4 or 7 days, to significantly improve neutrophil recovery following radiation-induced myelosuppression. Rhesus macaques were total body x-irradiated (250 kVp, TBI) to 600 cGy. Following TBI, two groups received peg-leridistim (n = 5) or leridistim (n = 4) at a dose of 600 microg/kg on day 1, while two other groups (both n = 4) received peg-leridistim at 200 microg/kg on day 1 and day 4, or day 1 and day 7. The irradiation controls (n = 7) received 0.1% autologous serum for 18 days. All peg-leridistim treatment schedules significantly improved all neutrophil-related parameters following TBI as compared with nontreated controls and were equivalent in effect when compared among themselves. Administration of a single high dose or two separate lower doses of peg-leridistim significantly improved neutrophil regeneration, in a manner equal to that of conventional daily or abbreviated every-other-day administration of leridistim in this nonhuman primate model of severe myelosuppression.

Veto-like activity of mesenchymal stem cells: functional discrimination between cellular responses to alloantigens and recall antigens.

Trans-differentiation of stem cells shows promise for use in tissue repair medicine. Although poorly defined, mesenchymal stem cells (MSC) appear useful for applications in repair medicine. Despite the low frequency of MSC, they are relatively easy to expand. The expression of MHC class II on MSC, however, could deter their use in repair medicine, since these molecules could stimulate an allogeneic host response. This study sought to compare the immune stimulatory and suppressive effects of MSC. Primary human MSC were cultured from bone marrow aspirates and then passaged at least three times before use in assays. Morphologically, MSC were symmetrical; were SH2(+), MHC class II(+), CD45(-), CD44(+), CD31(-), CD14(-), proly-4-hydroxylase(-); and showed normal karyotype patterns and elevated telomerase activities. MSC elicited significant stimulatory responses when cocultured with allogeneic PBMC. Despite the production of different types of growth factors, allogeneic effects of MSC could not be explained by the production of these growth factors. One-way MLR reactions were significantly blunted by third-party MSC. Similar suppression was not observed for responses to three different recall Ags. Based on these functional differences by MSC in responses to allo- and recall Ags, we examined whether MSC could exert veto-like functions. We showed that MSC could blunt the cytotoxic effects of allogeneic-induced effectors to mitogen-activated targets. The results showed that although MSC elicited allogeneic responses in a model that mimics a graft-vs-host reaction, they also exerted veto-like activity, but caused no effect on responses to recall Ags.