The Effects of Botulinum Toxin Type A on the Biological Behavior of Fibroblasts on Silicone Implants.

BACKGROUND: Capsular contracture is one of the most severe complications following breast augmentation surgery. It has been reported that botulinum toxin Type A (BTX-A) can inhibit capsular contracture, but the exact mechanisms remain unclear. Therefore, this study aims to explore the potential mechanisms behind BTX-A's inhibition of capsular contracture by observing its effects on the biological behavior of fibroblasts and its impact on the TGF-ß/Smad signaling pathway. METHODS: In vitro experiments involved culturing fibroblasts on PDMS surfaces, subsequently treating them with various concentrations of BTX-A. Fibroblast proliferation activity was assessed using the CCK-8 assay, while the migration and cytoskeletal morphology of the fibroblasts were meticulously examined. ELISA was utilized to quantify the expression of fibrosis-related cytokines. Gene and protein expressions related to the TGF-ß/Smad pathway were analyzed through real-time PCR and Western blotting techniques. RESULTS: BTX-A moderately enhanced the early proliferation and migration of fibroblasts on the surface of PDMS silicone sheets and reduced the synthesis of collagen types I and III. Furthermore, under the influence of BTX-A, the expression of TGF-ßR2 and α-SMA in the TGF-ß/Smad pathway was significantly inhibited. CONCLUSIONS: This study demonstrates that BTX-A can inhibit fibroblast differentiation by downregulating the expression of TGF-ßR2, thereby suppressing the TGF-ß/Smad pathway. This suggests a possible mechanism through which BTX-A mitigates capsular contracture. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effects of substrate topography on the regulation of human fibroblasts and capsule formation via modulating macrophage polarization.

The host-material interface is critical in determining the successful integration of medical devices into human tissue. The surface topography can regulate the fibrous capsule formation around implants through macrophage polarization, but the exact mechanism remains unclear. In this study, four types of microgrooves (10 or 50 µm in groove depths and 50 or 200 µm in groove widths) were fabricated on polydimethylsiloxane (PDMS) using lithography. The microgroove surfaces were characterized using the laser scanning confocal microscopy and fourier transform infrared spectroscopy. The effect of surface topography on macrophage phenotypes and conditioned medium (CM) collected from macrophages on human foreskin fibroblast 1 (HFF-1) were investigated. The result revealed that a deeper and narrower microgroove structure means a rougher surface. Macrophages tended to adhere and aggregate on group 50-50 surface (groove depths and widths of 50 µm). THP-1 cell polarized toward both inflammatory M1 and anti-inflammatory M2 macrophages on the surface of each group. Meanwhile, CM from macrophages culture on PDMS differentially up-regulated the proliferation, migration and fibrosis of HFF-1. Among them, the group 50-50 had the strongest promoting effect. In vivo, the inflammatory response and fibrotic capsule around the implants were observed at 1 week and 4 weeks. As time passed, the inflammatory response decreased, while the capsule thickness continued to increase. The rough material surface was more inclined to develop a severe fibrotic encapsulation. In conclusion, this finding further suggested a potential immunomodulatory effect of macrophages in mediating the fibrotic response to implants and facilitated the design of biomaterial interfaces for improving tissue integration.

Effect of different pulse numbers of transcranial magnetic stimulation on motor cortex excitability: Single-blind, randomized cross-over design.

AIMS: We aimed to investigate the effect of different pulse numbers of high-frequency repetitive transcranial magnetic stimulation (rTMS) over the motor cortex on cortical excitability in healthy participants. METHODS: Fifteen healthy participants received 600 and 1200 pulses of 5-Hz rTMS on separate days in a random order. Stimulation (duration, 2 seconds and interval, 1 seconds) was delivered over the left primary motor cortex for the hand, at 90% of resting motor threshold (rMT). The rMT and motor evoked potential (MEP) were measured before stimulation, and at 0 and 30 minutes after rTMS. RESULTS: No significant differences were observed between the two conditions for MEP (P = .919) or rMT (P = .266). Compared with baseline, MEP was increased significantly at 0 (P < .001) and 30 minutes (P < .001) after stimulation. After stimulation, rMT was decreased at 0 minute for the 600 and 1200 pulse conditions (P < .001), but had recovered by 30 minutes (P = .073). CONCLUSION: Subthreshold 5-Hz rTMS increased motor cortex excitability in healthy humans. However, the number of pulses may exhibit a ceiling effect in that beyond a certain point, that is, increasing the number of pulses may exhibit no further increase in cortical excitability.

Down-Regulation of Neuregulin1/ErbB4 Signaling in the Hippocampus Is Critical for Learning and Memory.

Hippocampal function is important for learning and memory, and dysfunction of the hippocampus has been linked to the pathophysiology of neuropsychiatric diseases such as schizophrenia. Neuregulin1 (NRG1) and ErbB4, two susceptibility genes for schizophrenia, reportedly modulate long-term potentiation (LTP) at hippocampal Schaffer collateral (SC)-CA1 synapses. However, little is known regarding the contribution of hippocampal NRG1/ErbB4 signaling to learning and memory function. Here, quantitative real-time PCR and Western blotting were used to assess the mRNA and protein levels of NRG1 and ErbB4. Pharmacological and genetic approaches were used to manipulate NRG1/ErbB4 signaling, following which learning and memory behaviors were evaluated using the Morris water maze, Y-maze test, and the novel object recognition test. Spatial learning was found to reduce hippocampal NRG1 and ErbB4 expression. The blockade of NRG1/ErbB4 signaling in hippocampal CA1, either by neutralizing endogenous NRG1 or inhibiting/ablating ErbB4 receptor activity, enhanced hippocampus-dependent spatial learning, spatial working memory, and novel object recognition memory. Accordingly, administration of exogenous NRG1 impaired those functions. More importantly, the specific ablation of ErbB4 in parvalbumin interneurons also improved learning and memory performance. The manipulation of NRG1/ErbB4 signaling in the present study revealed that NRG1/ErbB4 activity in the hippocampus is critical for learning and memory. These findings might provide novel insights on the pathophysiological mechanisms of schizophrenia and a new target for the treatment of Alzheimer's disease, which is characterized by a progressive decline in cognitive function.