Tracking the transcriptional host response from the acute to the regenerative phase of experimental pneumococcal meningitis

Despite the availability of effective antibiotic therapies, pneumococcal meningitis (PM) has a case fatality rate of up to 30% and causes neurological sequelae in up to half of the surviving patients. The underlying brain damage includes apoptosis of neurons in the hippocampus and necrosis in the cortex. Therapeutic options to reduce acute injury and to improve outcome from PM are severely limited.With the aim to develop new therapies a number of pharmacologic interventions have been evaluated. However, the often unpredictable outcome of interventional studies suggests that the current concept of the pathophysiologic events during bacterial meningitis is fragmentary. The aim of this work is to describe the transcriptomic changes underlying the complex mechanisms of the host response to pneumococcal meningitis in a temporal and spatial context using a well characterized infant rat model.

Long-term stability of surgical bone regenerative procedures of peri-implantitis lesions in a prospective case-control study over 3 years

Objectives: To evaluate the extent of bone fill over 3 years following the surgical treatment of peri-implantitis with bone grafting with or without a membrane. Material and Methods: In a non-submerged wound-healing mode, 15 subjects with 27 implants were treated with a bone substitute (Algipore®) alone and 17 subjects with 29 implants were treated with the bone substitute and a resorbable membrane (Osseoquest®). Implants with radiographic bone loss ≥1.8 mm following the first year in function and with bleeding and/or pus on probing were included. Following surgery, subjects were given systemic antibiotics (10 days) and rinsed with chlorhexidine. After initial healing, the subjects were enrolled in a strict maintenance programme. Results: Statistical analysis failed to demonstrate changes in bone fill between 1 and 3 years both between and within procedure groups. The mean defect fill at 3 years was 1.3 ± (SD) 1.3 mm if treated with the bone substitute alone and 1.6 ± (SD) 1.2 mm if treated with an adjunct resorbable membrane, (p=0.40). The plaque index decreased from approximately 40–10%, remaining stable during the following 2 years. Conclusion: Defect fill using a bone substitute with or without a membrane technique in the treatment of peri-implantitis can be maintained over 3 years.

Microfluidic wound-healing assay to assess the regenerative effect of HGF on wounded alveolar epithelium

We present a microfluidic epithelial wound-healing assay that allows characterization of the effect of hepatocyte growth factor (HGF) on the regeneration of alveolar epithelium using a flow-focusing technique to create a regular wound in the epithelial monolayer. The phenotype of the epithelial cell was characterized using immunostaining for tight junction (TJ) proteins and transmission electron micrographs (TEMs) of cells cultured in the microfluidic system, a technique that is reported here for the first time. We demonstrate that alveolar epithelial cells cultured in a microfluidic environment preserve their phenotype before and after wounding. In addition, we report a wound-healing benefit induced by addition of HGF to the cell culture medium (19.2 vs. 13.5 μm h(-1) healing rate).

A phase IIa randomized controlled pilot study evaluating the safety and clinical outcomes following the use of rhGDF-5/β-TCP in regenerative periodontal therapy

To present the safety profile, the early healing phase and the clinical outcomes at 24 weeks following treatment of human intrabony defects with open flap debridement (OFD) alone or with OFD and rhGDF-5 adsorbed onto a particulate β-tricalcium phosphate (β-TCP) carrier. Twenty chronic periodontitis patients, each with at least one tooth exhibiting a probing depth ≥6 mm and an associated intrabony defect ≥4 mm entered the study. Ten subjects (one defect/patient) were randomized to receive OFD alone (control) and ten subjects OFD combined with rhGDF-5/β-TCP. Blood samples were collected at screening, and at weeks 2 and 24 to evaluate routine hematology and clinical chemistry, rhGDF-5 plasma levels, and antirhGDF-5 antibody formation. Plaque and gingival indices, bleeding on probing, probing depth, clinical attachment level, and radiographs were recorded pre- and 24 weeks postsurgery. Comparable safety profiles were found in the two treatment groups. Neither antirhGDF-5 antibody formation nor relevant rhGDF-5 plasma levels were detected in any patient. At 6 months, treatment with OFD + rhGDF-5/β-TCP resulted in higher but statistically not significant PD reduction (3.7 ± 1.2 vs. 3.1 ± 1.8 mm; p = 0.26) and CAL gain (3.2 ± 1.7 vs. 1.7 ± 2.2 mm; p = 0.14) compared to OFD alone. In the tested concentration, the use of rhGDF-5/β-TCP appeared to be safe and the material possesses a sound biological rationale. Thus, further adequately powered, randomized controlled clinical trials are warranted to confirm the clinical relevance of this new approach in regenerative periodontal therapy. rhGDF-5/β-TCP may represent a promising new techology in regenerative periodontal therapy.

Wound healing following regenerative procedures in furcation degree III defects: histomorphometric outcomes

Degree III furcation involvements were surgically created at four first molars in each of three monkeys. Following 6 weeks of healing, full-thickness flaps were elevated. Following 24% EDTA gel conditioning, the defects were treated with one of the following: (1) enamel matrix proteins (EMD), (2) guided tissue regeneration (GTR) or (3) a combination EMD and GTR. The control defects did not receive any treatment. After 5 months of healing, the animals were sacrificed. Three 8 μm thick histological central sections, 100 μm apart, were used for histomorphometric analysis in six zones of each tooth either within the furcation area or on the pristine external surface of the root. In all specimens, new cementum with inserting collagen fibres was formed. Following GTR or GTR + EMD, cementum was formed up to and including the furcation fornix indicating complete regeneration on the defect periphery. Periodontal ligament fibres were less in all four modalities compared to pristine tissues. In the teeth treated with GTR and GTR + EMD a higher volume of bone and periodontal ligament tissues was observed compared to EMD. After 5 months of healing, regenerated tissues presented quantitative differences from the pristine tissues. In the two modalities where GTR alone or combined with EMD was used, the regenerated tissues differed in quantity from the EMD-treated sites.

Multi-stage ytterbium fiber-amplifier seeded by a gain-switched laser diode

We demonstrated all-fiber amplification of 11 ps pulses from a gain-switched laser diode at 1064 nm. The diode was driven at a repetition rate of 40 MHz and delivered 13 µW of fiber-coupled average output power. For the low output pulse energy of 325 fJ we have designed a multi-stage core pumped pre-amplifier in order to keep the contribution of undesired amplified spontaneous emission as low as possible. By using a novel time-domain approach for determining the power spectral density ratio (PSD) of signal to noise, we identified the optimal working point for our pre-amplifier. After the pre-amplifier we reduced the 40 MHz repetition rate to 1 MHz using a fiber coupled pulse-picker. The final amplification was done with a cladding pumped Yb-doped large mode area fiber and a subsequent Yb-doped rod-type fiber. With our setup we reached a total gain of 73 dB, resulting in pulse energies of >5.6 µJ and peak powers of >0.5 MW. The average PSD-ratio of signal to noise we determined to be 18/1 at the output of the final amplification stage.

Regenerative capacity of individual liver lobes in the microsurgical mouse model

In the development of microsurgical mouse models of hepatic regeneration and repair, lobe-specific regenerative responses were observed. We therefore determined the hepatic regenerative capacity of individual mouse liver lobes. In mice, 26, 60, 75, and 83% of total liver mass was resected. Bromo-deoxyuridine (BrdU) was injected prior to liver harvest and the BrdU labeling index determined in all remaining individual liver lobes. BrdU-positive nuclei were seen in all liver lobes after the 26 and 60% resection, but significantly fewer were detected in the caudate lobe. In the 75% group, equally distributed positive nuclei were found. However, BrdU labeling was scant in the 83% group. In microsurgical mouse liver-regeneration models, the average hepatic response depends on amount of liver tissue resected and on the remaining liver lobe. BrdU incorporation can vary significantly among individual lobes. The lobe-specific differences observed may prove valuable in further investigations of hepatic regeneration and repair.

Pattern of mineralization after regenerative periodontal therapy with enamel matrix proteins

A derivative (EMD) of enamel matrix proteins (EMPs) is used for periodontal regeneration because EMPs are believed to induce the formation of acellular extrinsic fiber cementum (AEFC). Other reports, however, indicate that EMPs have osteogenic potential. The aim of this study was to characterize the nature of the tissue that forms on the root surface following application of EMD. Ten human teeth affected by periodontitis and scheduled for extraction were treated with EMD. Four to six weeks later, they were extracted and processed for analysis by light microscopy and transmission electron microscopy. Immunocytochemistry with antibodies against bone sialoprotein (BSP) and osteopontin (OPN) was performed to determine the mineralization pattern. The newly formed tissues on the root were thick and contained embedded cells. Small mineralization foci were regularly seen, and large organic matrix patches were occasionally seen, but a distinct mineralization front was lacking. While labeling for BSP was always associated with small mineralization foci and large matrix patches, OPN labeling was seen inconsistently. It is concluded that tissues resembling either cellular intrinsic fiber cementum or a type of bone were observed. The mineralization pattern mostly resembled that found in bone, except for a few areas that exhibited a hitherto undescribed mineralization pattern.

Stem cells as tools in regenerative therapy for retinal degeneration

OBJECTIVE: To describe the use of stem cells (SCs) for regeneration of retinal degenerations. Regenerative medicine intends to provide therapies for severe injuries or chronic diseases where endogenous repair does not sufficiently restore the tissue. Pluripotent SCs, with their capacity to give rise to specialized cells, are the most promising candidates for clinical application. Despite encouraging results, a combination with up-to-date tissue engineering might be critical for ultimate success. DESIGN: The focus is on the use of SCs for regeneration of retinal degenerations. Cell populations include embryonic, neural, and bone marrow-derived SCs, and engineered grafts will also be described. RESULTS: Experimental approaches have successfully replaced damaged photoreceptors and retinal pigment epithelium using endogenous and exogenous SCs. CONCLUSIONS: Stem cells have the potential to significantly impact retinal regeneration. A combination with bioengineering may bear even greater promise. However, ethical and scientific issues have yet to be solved.

Leptin effects on the regenerative capacity of human periodontal cells

Obesity is increasing throughout the globe and characterized by excess adipose tissue, which represents a complex endocrine organ. Adipose tissue secrets bioactive molecules called adipokines, which act at endocrine, paracrine, and autocrine levels. Obesity has recently been shown to be associated with periodontitis, a disease characterized by the irreversible destruction of the tooth-supporting tissues, that is, periodontium, and also with compromised periodontal healing. Although the underlying mechanisms for these associations are not clear yet, increased levels of proinflammatory adipokines, such as leptin, as found in obese individuals, might be a critical pathomechanistic link. The objective of this study was to examine the impact of leptin on the regenerative capacity of human periodontal ligament (PDL) cells and also to study the local leptin production by these cells. Leptin caused a significant downregulation of growth (TGFβ1, and VEGFA) and transcription (RUNX2) factors as well as matrix molecules (collagen, and periostin) and inhibited SMAD signaling under regenerative conditions. Moreover, the local expression of leptin and its full-length receptor was significantly downregulated by inflammatory, microbial, and biomechanical signals. This study demonstrates that the hormone leptin negatively interferes with the regenerative capacity of PDL cells, suggesting leptin as a pathomechanistic link between obesity and compromised periodontal healing.