Application of extracellular vesicles from mesenchymal stem cells promotes hair growth by regulating human dermal cells and follicles

BACKGROUND Dermal papillae(DP)and outer root sheath(ORS)cells play important roles in hair growth and regeneration by regulating the activity of hair follicle(HF)cells.AIM To investigate the effects of human mesenchymal stem cell-derived extracellular vesicles(hMSC-EVs)on DP and ORS cells as well as HFs.EVs are known to regulate various cellular functions.However,the effects of hMSC-EVs on hair growth,particularly on human-derived HF cells(DP and ORS cells),and the possible mechanisms underlying these effects are unknown.METHODS hMSC-EVs were isolated and characterized using transmission electron microscopy,nanoparticle tracking analysis,western blotting,and flow cytometry.The activation of DP and ORS cells was analyzed using cellular proliferation,migration,western blotting,and real-time polymerase chain reaction.HF growth was evaluated ex vivo using human HFs.RESULTS Wnt3a is present in a class of hMSC-EVs and associated with the EV membrane.hMSC-EVs promote the proliferation of DP and ORS cells.Moreover,they translocateβ-catenin into the nucleus of DP cells by increasing the expression ofβ-catenin target transcription factors(Axin2,EP2 and LEF1)in DP cells.Treatment with hMSC-EVs also promoted the migration of ORS cells and enhanced the expression of keratin(K)differentiation markers(K6,K16,K17,and K75)in ORS cells.Furthermore,treatment with hMSC-EVs increases hair shaft elongation in cultured human HFs.CONCLUSION These findings suggest that hMSC-EVs are potential candidates for further preclinical and clinical studies on hair loss treatment.

Epidermal stem cells and skin tissue engineering in hair follicle regeneration

The reconstitution of a fully organized and functional hair follicle from dissociated cells propagated under defined tissue culture conditions is a challenge stillpending in tissue engineering. The loss of hair follicles caused by injuries or pathologies such as alopecia not only affects the patients' psychological well-being, but also endangers certain inherent functions of the skin. It is then of great interest to find different strategies aiming to regenerate or neogenerate the hair follicle under conditions proper of an adult individual. Based upon current knowledge on the epithelial and dermal cells and their interactions during the embryonic hair generation and adult hair cycling, many researchers have tried to obtain mature hair follicles using different strategies and approaches depending on the causes of hair loss. This review summarizes current advances in the different experimental strategies to regenerate or neogenerate hair follicles, with emphasis on those involving neogenesis of hair follicles in adult individuals using isolated cells and tissue engineering. Most of these experiments were performed using rodent cells, particularly from embryonic or newborn origin. However, no successful strategy to generate human hair follicles from adult cells has yet been reported. This review identifies several issues that should be considered to achieve this objective. Perhaps the most important challenge is to provide threedimensional culture conditions mimicking the structure of living tissue. Improving culture conditions that allow the expansion of specific cells while protecting their inductive properties, as well as methods for selecting populations of epithelial stem cells, should give us the necessary tools to overcome the difficulties that constrain human hair follicle neogenesis. An analysis of patent trends shows that the number of patent applications aimed at hair follicle regeneration and neogenesis has been increasing during the last decade. This field is attractive not only to academic researchers but also to the companies that own almost half of the patents in this field.

NOTCH3 is expressed in human apical papilla and in subpopulations of stem cells isolated from the tissue

NOTCH plays a role in regulating stem cell function and fate decision.It is involved in tooth development and injury repair.Information regarding NOTCH expression in human dental root apical papilla(AP)and its residing stem cells(SCAP)is limited.Here we investigated the expression of NOTCH3,its ligand JAG1,and mesenchymal stem cell markers CD146 and STRO-1 in the AP or in the primary cultures of SCAP isolated from AP.Our in situ immunostaining showed that in the AP NOTCH3 and CD146 were co-expressed and associated with blood vessels having NOTCH3 located more peripherally.In cultured SCAP,NOTCH3 and JAG1 were co-expressed.Flow cytometry analysis showed that 7%,16%and 98%of the isolated SCAP were positive for NOTCH3,STRO-1 and CD146,respectively with a rare 1.5%subpopulation of SCAP co-expressing all three markers.The expression level of NOTCH3 reduced when SCAP underwent osteogenic differentiation.Our findings are the first step towards defining the regulatory role of NOTCH3 in SCAP fate decision.

Proteomic profiling of various human dental stem cells-a systematic review

BACKGROUND The proteomic signature or profile best describes the functional component of a cell during its routine metabolic and survival activities.Additional complexity in differentiation and maturation is observed in stem/progenitor cells.The role of functional proteins at the cellular level has long been attributed to anatomical niches,and stem cells do not deflect from this attribution.Human dental stem cells(hDSCs),on the whole,are a combination of mesenchymal and epithelial coordinates observed throughout craniofacial bones to pulp.AIM To specify the proteomic profile and compare each type of hDSC with other mesenchymal stem cells(MSCs)of various niches.Furthermore,we analyzed the characteristics of the microenvironment and preconditioning changes associated with the proteomic profile of hDSCs and their influence on committed lineage differentiation.METHODS Literature searches were performed in PubMed,EMBASE,Scopus,and Web of Science databases,from January 1990 to December 2018.An extra inquiry of the grey literature was completed on Google Scholar,ProQuest,and OpenGrey.Relevant MeSH terms(PubMed)and keywords related to dental stem cells were used independently and in combination.RESULTS The initial search resulted in 134 articles.Of the 134 full-texts assessed,96 articles were excluded and 38 articles that met the eligibility criteria were reviewed.The overall assessment of hDSCs and other MSCs suggests that differences in the proteomic profile can be due to stem cellular complexity acquired from varied tissue sources during embryonic development.However,our comparison of the proteomic profile suffered inconsistencies due to the heterogeneity of various hDSCs.We believe that the existence of a heterogeneous population of stem cells at a given niche determines the modalities of regeneration or tissue repair.Added prominences to the differences present between various hDSCs have been reasoned out.CONCLUSION Systematic review on proteomic studies of various hDSCs are promising as an eye-opener for revisiting the proteomic profile and in-depth analysis to elucidate more refined mechanisms of hDSC functionalities.

Are human dental papilla-derived stem cell and human brain-derived neural stem cell transplantations suitable for treatment of Parkinson’s disease?

Transplantation of neural stem cells has been reported as a possible approach for replacing impaired dopaminergic neurons. In this study, we tested the efficacy of early-stage human dental papilla-derived stem cells and human brain-derived neural stem cells in rat models of 6-hydroxydopamine-induced Parkinson＇s disease. Rats received a unilateral injection of 6-hydroxydopamine into right medial forebrain bundle, followed 3 weeks later by injections of PBS, early-stage human dental papilla-derived stem cells, or human brain-derived neural stem cells into the ipsilateral striatum. All of the rats in the human dental papilla-derived stem cell group died from tumor formation at around 2 weeks following cell transplantation. Postmortem examinations revealed homogeneous malignant tumors in the striatum of the human dental papilla-derived stem cell group. Stepping tests revealed that human brain-derived neural stem cell transplantation did not improve motor dysfunction. In apomorphine-induced rotation tests, neither the human brain-derived neural stem cell group nor the control groups （PBS injection） demonstrated significant changes. Glucose metabolism in the lesioned side of striatum was reduced by human brain-derived neural stem cell transplantation. [18F]-FP-CIT PET scans in the striatum did not demonstrate a significant increase in the human brain-derived neural stem cell group. Tyrosine hydroxylase （dopaminergic neuronal marker） staining and G protein-activated inward rectifier potassium channel 2 （A9 dopaminergic neuronal marker） were positive in the lesioned side of striatum in the human brain-derived neural stem cell group. The use of early-stage human dental papilla-derived stern cells confirmed its tendency to form tumors. Human brain-derived neural stem cells could be partially differentiated into dopaminergic neurons, but they did not secrete dopamine.

Application of dental stem cells in three-dimensional tissue regeneration

Dental stem cells can differentiate into different types of cells.Dental pulp stem cells,stem cells from human exfoliated deciduous teeth,periodontal ligament stem cells,stem cells from apical papilla,and dental follicle progenitor cells are five different types of dental stem cells that have been identified during different stages of tooth development.The availability of dental stem cells from discarded or removed teeth makes them promising candidates for tissue engineering.In recent years,three-dimensional(3D)tissue scaffolds have been used to reconstruct and restore different anatomical defects.With rapid advances in 3D tissue engineering,dental stem cells have been used in the regeneration of 3D engineered tissue.This review presents an overview of different types of dental stem cells used in 3D tissue regeneration,which are currently the most common type of stem cells used to treat human tissue conditions.

新型生物陶瓷材料对人根尖牙乳头干细胞增殖及成骨分化的影响

目的评估新型生物陶瓷类材料c-Root SP对人根尖牙乳头干细胞(hSCAPs)的细胞增殖及骨诱导能力。方法制备不同浓度c-Root SP浸提液,采用CCK-8法检测其对hSCAPs的细胞增殖情况,使用碱性磷酸酶(ALP)活性测定法测定ALP酶水平和茜素红染色法观察钙化结节形成情况,数据采用单因素方差分析,与iRootSP对比,评价c-Root SP促进细胞增殖及骨诱导能力。结果c-Root SP对hSCAPs的细胞增殖具有浓度依赖性,1/10浓度浸提液增殖水平最好,c-Root SP1/5、1/10、1/1000浓度浸提液对hSCAPs的细胞增殖的影响显著高于同浓度iRoot SP浸提液(P<0.05)。成骨方面,矿化诱导7天,iRoot SP ALP活性显著高于c-Root SP(P<0.05),矿化诱导14天c-Root SP矿化结节显著多于iRoot SP。结论c-Root SP具有对hSCAPs的良好细胞增殖及骨诱导能力,与iRoot SP相似。

人脐带干细胞外泌体对人毛乳头细胞增殖的影响

目的探究人脐带间充质干细胞外泌体(hUCMSC-Exos)对人毛乳头细胞(HDPCs)增殖的影响,并对hUCMSC-Exos促毛发生长作用的机制进行初步探索。方法二步酶法分离HDPCs并进行体外培养,培养人脐带间充质干细胞(hUC-MSCs),收集细胞培养上清,通过超高速离心法提取外泌体,并对其进行电镜、粒径及表面标记物鉴定。双氢睾酮(dihydrotestosterone,DHT)诱导HDPCs建立雄激素性脱发细胞模型。将hUCMSC-Exos与HDPCs共培养,采用细胞增殖试验(EdU)检测诱导的HDPCs的相对活力。Real-time qPCR检测碱性磷酸酶(ALP)表达水平、Western blot检测β-catenin、Wnt10b、GSK-3β在蛋白水平的表达。结果所获取的HDPCs、h UC-MSCs和hUCMSC-Exos均符合毛乳头细胞、间充质干细胞及外泌体特征。EdU阳性细胞数显著增加,外泌体可有效促进HDPCs增殖(P<0.05),增强HDPCs活力,减轻DHT造成的损伤(P<0.05)。Real-time qPCR显示外泌体可增强ALP基因表达水平(P<0.05),增强毛囊诱导能力;Western blot证实β-catenin、Wnt10b、GSK-3β在蛋白水平的表达均有差异(P<0.05)。结论hUCMSCExos可促进DHT诱导的HDPCs增殖,增强其毛囊再生修复能力,其机制可能与激活Wnt/β-catenin信号通路有关。

根尖牙乳头干细胞来源凋亡囊泡对巨噬细胞糖酵解相关酶的表达及炎症表型影响的初探研究

目的:探究根尖牙乳头干细胞(SCAP)来源的凋亡囊泡(apoVs)是否通过影响糖酵解相关酶调控巨噬细胞(BMDMs)炎症表型,进而对炎症反应产生调节作用。方法:体外培养鉴定人源SCAP,经星形孢菌素诱导凋亡后提取apoVs,利用扫描电镜、流式细胞术等对其进行表征鉴定。分别空白处理、脂多糖(LPS)处理、LPS同apoVs共处理大鼠骨髓来源的BMDMs,利用流式细胞术检测促炎表型BMDMs表面标志分子CD80、CD86的表达,利用Western blot检测BMDMs糖酵解相关酶的表达。结果:根尖牙乳头干细胞来源的apoVs能被BMDMs摄取,促炎表型标志分子CD80、CD86的表达下调,糖酵解相关酶葡萄糖转运蛋白(GLUT)1、GLUT3的表达显著下调(P<0.05)。结论:SCAP来源apoVs能降低促炎型BMDMs的分布,并对其糖酵解相关酶的表达产生影响。

WDR63促进人根尖牙乳头干细胞成神经分化功能

目的:研究WD重复结构域63(WDR63)对人根尖牙乳头干细胞(SCAPs)体外成神经分化能力的作用。方法:通过实时荧光定量PCR检测未转染慢病毒SCAPs中WDR63基因在成神经分化诱导3、6、9 d的表达变化,利用慢病毒转染分别获得WDR63稳定过表达和敲低的SCAPs,通过类神经球形成实验对各组SCAPs进行神经分化诱导,对类神经球的直径进行定量分析,免疫荧光染色实验检测SCAPs中巢蛋白(Nestin)和βⅢ-微管蛋白(βⅢ-tubulin)的表达,实时荧光定量PCR实验检测神经分化相关指标βⅢ-tubulin、神经源性分化蛋白(NeuroD)、神经细胞黏附分子(NCAM)和Nestin基因的表达。结果:未转染慢病毒SCAPs中WDR63的表达量在成神经分化后的3、6、9 d逐渐增加(P<0.05);过表达WDR63后,WDR63基因(P<0.001)和蛋白表达增加,神经球直径增加(P<0.01),Nestin和βⅢ-tubulin神经球样细胞荧光强度增加(P<0.01),βⅢ-tubulin、NeuroD、NCAM和Nestin基因表达升高(P<0.05);敲低WDR63后,WDR63基因(P<0.01)和蛋白的表达降低,神经球直径降低(P<0.05),Nestin和βⅢ-tubulin神经球样细胞荧光强度减少(P<0.05),βⅢ-tubulin、NeuroD、NCAM和Nestin基因表达降低(P<0.05)。结论:WDR63可促进SCAPs的成神经分化功能。

消退素E1对炎症微环境下根尖牙乳头细胞的影响

目的 探讨消退素E1(resolvin E1,RvE1)对脂多糖(Lipopolysaccharide, LPS)诱导的炎症微环境下根尖牙乳头细胞(apical papilla cells, APCs)成牙本质方向分化及细胞自噬的影响。方法 将人APCs分为对照组、LPS组和LPS RvE1组,应用MTT检测细胞增殖情况,应用realtime-PCR检测成牙本质方向分化相关基因表达情况,应用茜素红染色及氯化十六烷基吡啶半定量分析检测APCs矿化结节形成情况,应用Western blot检测APCs自噬相关蛋白表达情况。结果 与对照组比较,LPS组的APCs增殖受到抑制,成牙本质方向分化及矿化结节形成减弱,细胞自噬增强(P<0.05)。与LPS组比较,LPS RvE1组的APCs增殖、成牙本质方向分化及矿化结节形成均增强,细胞自噬减弱(P<0.05)。结论 RvE1促进炎症微环境下APCs成牙本质方向分化和降低自噬。

根尖牙乳头干细胞成骨分化的研究进展

根尖牙乳头干细胞(stem cells from apical papilla,SCAP)具有很强的多系分化潜能,其中成骨分化可以应用于骨组织再生,为口腔颌骨缺损治疗提供新思路。成骨分化是个复杂的网络调控过程,诸如各种细胞因子、表观遗传物质、各种信号分子和信号通路等内源性物质均可产生不同程度的影响。这些因素相互作用可以促进SCAP的增殖、迁移和成骨分化,但其在SCAP成骨分化的不同进程中的具体机制和内在联系各不相同。对近年来有关促进SCAP成骨分化的各种因素及其可能的调控机制研究文献进行综述,以期为其进一步的应用研究提供新信息。

IL-34介导的NF-кB信号通路对根尖牙乳头干细胞成牙成骨定向分化的调节作用

目的:探讨白细胞介素-34(IL-34)介导的核因子кB(NF-кB)对根尖牙乳头干细胞(SCAPs)成牙/成骨定向分化调节作用。方法:使用酶消化法从小鼠根尖牙乳头组织传代培养SCAPs;流式细胞术鉴定SCAPs中CD44、CD90、CD45及集落刺激因子1受体(CSF-1R)的表达;实验分为4组:空白对照组、IL-34组(100 ng/mL IL-34)、CSF-1R组(100 ng/mL IL-34+25 ng/mL anti-CSF-1R)、NF-кB组(100 ng/mL IL-34+1umol/L BMS-345541)。通过蛋白质印迹法(Western blot)分析各组30、60、120 min时SCAPs胞浆中NF-кB关键蛋白p-IкBα、IкBα、p-P65及P65蛋白的表达情况;矿化诱导4组SCAPs 3、7、14 d时,茜素红染色和半定量分析比较各组细胞的矿化结节形成能力;通过RT-qPCR检测各组SCAPs中成骨相关基因Runt相关转录因子-2(RUNX2)、牙本质涎磷蛋白(DSPP)、骨钙素(OCN)mRNA水平。结果:流式细胞术显示,SCAPs中CD44(90.4%)、CD90(93.5%)阳性表达,造血干细胞CD45(3.1%)阴性表达,SCAPs表达CSF-1R(23.2%)阳性。与对照组比较,IL-34组SCAPs胞浆蛋白内p-IкBα、p-P65表达水平上调,矿化诱导3、7、14 d矿化结节形成量增多,细胞中RUNX2、DSPP、OCN mRNA相对表达量升高,差异均有统计学意义(P<0.05)。与IL-34组比较,CSF-1R组和NF-кB组SCAPs胞浆蛋白内p-IкBα、p-P65表达水平下调(P<0.05),矿化诱导3、7、14 d矿化结节形成量减少,细胞中RUNX2、DSPP、OCN mRNA相对表达量降低,差异均有统计学意义(P<0.05)。结论:IL-34可通过IL-34/CSF-1R调节SCAPs中NF-кB信号通路,并通过IL-34/CSF-1R/NF-кB信号调节SCAPs的成牙/成骨定向分化能力。

Extracellular vesicles derived from human dental mesenchymal stem cells stimulated with low-intensity pulsed ultrasound alleviate inflammation-induced bone loss in a mouse model of periodontitis

Extracellular vesicles(EVs)derived from mesenchymal stem cells(MSCs)have emerged as a new mode of intercellular crosstalk and are responsible for many of the thera-peutic effects of MSCs.To promote the application of MSC-EVs,recent studies have focused on the manipulation of MSCs to improve the production of EVs and EV-mediated activities.The current paper details an optimization method using non-invasive low-intensity pulsed ul-trasound(LIPUS)as the stimulation for improving oral MSC-EV production and effectiveness.Stem cells from apical papilla(SCAP),a type of oral mesenchymal stem cell,displayed inten-sity-dependent pro-osteogenic and anti-inflammatory responses to LIPUS without significant cytotoxicity or apoptosis.The stimuli increased the secretion of EVs by promoting the expres-sion of neutral sphingomyelinases in SCAP.In addition,EVs from LIPUS-induced SCAP exhibited stronger efficacy in promoting the osteogenic differentiation and anti-inflammation of peri-odontal ligament cells in vitro and alleviating oral inflammatory bone loss in vivo.In addition,LIPUS stimulation affected the physical characteristics and miRNA cargo of SCAP-EVs.Further investigations indicated that miR-935 is an important mediator of the pro-osteogenic and anti-inflammatory capabilities of LIPUS-induced SCAP-EVs.Taken together,these findings demonstrate that LIPUS is a simple and effective physical method to optimize SCAP-EV produc-tion and efficacy.

Apical bud上皮诱导脂肪间充质干细胞向成牙本质样细胞分化的研究

目的:通过体外及体内实验探讨大鼠切牙Apical bud上皮细胞诱导大鼠脂肪来源间充质干细胞向成牙本质细胞分化的能力。方法:分离培养大鼠脂肪间充质干细胞、Apical bud上皮细胞,制备Apical bud上皮条件诱导液并体外对ADSCs诱导7d,通过实时定量PCR方法检测成牙本质关键基因DMP-1及DSPP的表达。制备ADSCs及Apical bud上皮重组细胞团进行大鼠肾被膜下移植,8W后取材,分别采用HE染色、Masson三色法和免疫组化方法对移植生成物进行组织学检测。结果:Apical bud上皮诱导ADSCs后DMP-1及DSPP m R NA表达水平显著高于对照组。体内移植8W后H E染色可见管样牙本质和骨样牙本质样结构,Masson三色法可以观察到有绿色的牙本质样结构,免疫组化检测中CK14染色阳性,DSPP染色阳性。结论:Apical bud上皮细胞在体外能够诱导ADSCs向成牙本质细胞分化,且细胞重组在体内可以构建出牙本质样结构。

Plant stem cells and their regulations in shoot apical meristems

Stem cells in plants,established during embry-ogenesis,are located in the centers of the shoot apical meristem(SAM)and the root apical meristem(RAM).Stem cells in SAM have a capacity to renew themselves and to produce new organs and tissues indefinitely.Although fully differentiated organs such as leaves do not contain stem cells,cells in such organs do have the capacity to re-establish new stem cells,especially under the induction of phytohormones in vitro.Cytokinin and auxin are critical in creating position signals in the SAM to maintain the stem cell organizing center and to position the new organ primordia,respectively.This review addresses the distinct features of plant stem cells and focuses on how stem cell renewal and differentiation are regulated in SAMs.

S100A9促进胚胎干细胞向神经前体细胞分化中顶端—基底极化和神经管形成

目的 探讨胚胎干细胞(embryonic stem cells, ESCs)向神经前体细胞(neural progenitor cells, NPCs)分化过程中S100A9促进顶端-基底极化(apical-basal polarity, ABP)和神经管结构形成的作用。方法 采用免疫荧光观察体外培养ESCs向NPCs分化1、2、3和6 d时细胞管腔样结构排列,神经巢蛋白(Nestin)和配对盒因子6(paired box protein 6, Pax-6)表达,以及S100A9、N-钙粘蛋白(N-cadherin)和zonula occludens 1(ZO-1)定位变化。慢病毒转染下调S100A9及外源性S100A9重组蛋白干预细胞后检测对N-cadherin和ZO-1定位的影响。Western blot分析S100A9在ESCs向NPCs分化过程中不同时间点表达差异,同时观察S100A9对Notch1及下游centromere binding factor 1(CBF1)的调控。结果 ESCs在体外定向分化后第3天起表达Nestin和Pax-6,N-cadherin和ZO-1定位于顶端侧并呈现出ABP特征性神经玫瑰花状结构(neural rosette),细胞在第6天形成神经管结构。S100A9在分化后第3天起表达明显增加(P<0.01)并定位于顶端侧。下调S100A9后ESCs仍能分化为NPCs,但neural rosette数量明显减少(P<0.01)。予以外源性S100A9重组蛋白可部分恢复neural rosette数量(P<0.01)。在此分化过程中,下调S100A9降低Notch1及下游CBF1表达。结论 S100A9可能通过调控Notch1/CBF1参与ESCs向NPCs分化过程中ABP和神经管结构形成。

IL-34介导的NF-кB信号通路对根尖牙乳头干细胞增殖、迁移的调节作用

目的:探讨白细胞介素-34(IL-34)能否通过调控核因子-кB(NF-кB)影响根尖牙乳头干细胞(SCAPs)增殖、迁移。方法:取小鼠中切牙根尖牙乳头组织,酶消化法传代培养SCAPs;流式细胞术鉴定SCAPs表面CD44、CD45、CD90以及CSF-1R的表达;将SCAPs分为4组:空白对照组、IL-34组(100 ng/mL IL-34)、CSF-1R组(100 ng/mL IL-34+25 ng/mL anti-CSF-1R)和NF-кB组(100 ng/mL IL-34+1μmol/L BMS-345541);Western blotting分析各组中,30、60、120 min时SCAPs细胞质、细胞核中p-IкBα、IкBα、p-P65及p65蛋白的相对表达量;Transwell实验分析各组SCAPs迁移能力;将每组IL-34更换为50 ng/mL,CCK-8分析各组SCAPs增殖变化情况。结果:流式细胞术鉴定SCAPs表达CD44、CD90阳性,CD45阴性;SCAPs表面表达CSF-1R;与对照组SCAPs相比,IL-34处理后的SCAPs细胞质、细胞核内p-IкBα、p-P65与细胞质、细胞核中p-P65相对表达量显著增加,SCAPs增殖、迁移能力增强。与IL-34组相比CSF-1R组、NF-кB组内SCAPs增殖、迁移能力降低,SCAPs细胞质、细胞核中p-IкBα、p-P65与胞核中p-P65蛋白表达明显减少。结论:IL-34可调节SCAPs中NF-кB信号通路,并通过NF-кB信号通路调节IL-34的增殖和迁移。

毛囊微型化发生的机制与最新研究进展

雄激素性脱发(androgenetic alopecia,AGA)又称为脂溢性脱发,是临床上最常见的脱发类型,毛囊微型化是该病发生发展过程中的重要特征。目前研究已发现有很多原因可诱导毛囊微型化的发生,一方面通过促使患者头皮毛囊真皮乳头细胞(dermal papilla cell,DPC)分泌毛囊抑制因子、DPC发生凋亡和自噬障碍,另一方面通过毛周微循环形成障碍、毛囊干细胞的过度耗竭及真皮鞘细胞的丢失与纤维化进一步加剧了AGA的发生发展,最终导致患者的毛发由最初的终毛逐渐转换为细小的毳毛。本综述从不同角度探讨毛囊微型化的病因与机制,为未来对AGA的有效治疗提供帮助。

雌激素缺乏对大鼠根尖牙乳头干细胞增殖及牙向/骨向分化能力的影响

目的:探讨雌激素缺乏对大鼠根尖牙乳头干细胞(SCAPs)增殖及牙向/骨向分化能力的影响。方法:选取20只8周龄雌性SD大鼠随机分为假手术(Sham)组和卵巢去势(OVX)组,每组各10只。全麻下OVX组摘除双侧卵巢,Sham组行相同切口保留双侧卵巢,术前、术后1个月分别检测两组大鼠血清雌二醇水平。1个月后每组各处死5只大鼠,分离切牙根尖牙乳头组织,酶消化法分离培养两组SCAPs,采用MTT、碱性磷酸酶(ALP)活性检测、实时荧光定量PCR、Western blot检测雌激素缺乏对大鼠SCAPs增殖及成牙/成骨向分化能力的影响。将两组SCAPs细胞以明胶海绵为载体分别植入对应组别大鼠肾被膜下,8周后取出植入组织,使用数字化X线牙片机对取出团块曝光成像及HE染色观察其矿化能力。结果:OVX组大鼠去势1个月后血清雌二醇水平显著低于术前(P<0.001),Sham组大鼠血清雌二醇水平术前、术后差异无统计学意义(P>0.05)。MTT结果显示,OVX组SCAPs增殖能力显著下降(P<0.001)。ALP活性检测结果显示,OVX组SCAPs的ALP活性低于Sham组(P<0.001)。实时荧光定量PCR和Western blot结果均表明OVX组SCAPs的牙本质涎磷蛋白(DSPP)、成骨细胞特异性转录因子Osterix(OSX)、骨钙素(OCN)等成牙/成骨相关基因和蛋白表达低于Sham组(P<0.01)。体内移植结果显示,Sham组形成密度较高的较规则牙髓-牙本质复合体,而OVX组形成不规则结构。结论:雌激素缺乏减弱大鼠SCAPs的增殖及牙向/骨向分化能力。