Effect of mechanical stimulation on dental pulp stem cells

doi:10.3969/j.issn.2095-4344.2098

Abstract

Abstract:

BACKGROUND: Mechanical stimulation plays a necessary regulatory role in developing and repairing many organs and tissues in the human body. Except for biochemical factors, mechanical factors are considered as key regulatory factors that affect the behavior and function of dental pulp stem cells.

OBJECTIVE: To review the role and effect of cellular mechanical stimulation on the biological behavior of dental pulp stem cells.

METHODS: PubMed, Embase, Medline and CNKI databases were searched for relevant literatures using the keywords of “human dental pulp stem cells (hDPSCs), mechanical strain, mechanical stretch, mechanical tension, shear stress, cell proliferation, osteogenesis differentiation” in English and Chinese, respectively. Fifty-six articles were finally eligible for review, which were closely related to the proliferation and differentiation of dental pulp stem cells under cellular mechanical stimulation.

RESULTS AND CONCLUSION: Cellular mechanical stimulation is an important biological factor affecting cell proliferation, differentiation, apoptosis and protein expression. Dental pulp stem cells are mesenchymal stem cells derived from the dental pulp tissue, and their biological behaviors are also affected by cellular mechanical stimulation. Cellular mechanical stimulation is involved in the proliferation, odontogenesis/osteogenesis of dental pulp stem cells. When the dentin is subjected to fluid flow forces, mechanoreceptors are activated to regulate and maintain the integrity of tooth structure. Signal pathways that mediate the biological behavior of dental pulp stem cells include MAPK, Wnt, Akt, BMP-7, and Nrf2/HO-1, which are involved in promoting and inhibiting the proliferation and odontogenesis/osteogenesis of dental pulp stem cells to varying degrees.

Key words:

dental pulp stem cell, cell proliferation, osteogenic differentiation, odontogenic dentin stem cells, mechanical properties, cellular mechanics, biological behavior, tooth regeneration and tissue engineering

CLC Number:

Li Junqing, Wu Jiayuan.

Effect of mechanical stimulation on dental pulp stem cells [J]. Chinese Journal of Tissue Engineering Research, 2020, 24(25): 4054-4059.

Figures/Tables 1

2 结果 Results 2.1 细胞力学刺激诱导牙髓干细胞增殖牙髓干细胞是一种对机械力敏感的细胞，它能够识别机械变化并将这些信息转化为细胞反应[27]。为了检测对细胞力学机械应力的反应，YANG等[28]采用四点弯曲应变系统对牙髓干细胞进行循环单轴压应力刺激，在3 h和6 h后骨形态发生蛋白2表达明显上调，其机械刺激显著促进牙髓干细胞增殖。此外，HATA等[29]将牙髓干细胞接种到大小为2.0 cm×2.0 cm拉伸室中进行一定时间的单轴机械拉伸，发现机械拉伸力可以促进牙髓干细胞的增殖，而单轴拉伸力是颌骨运动产生的机械力，也是压力和剪切应力的一种[30-31]。HAN等[32]研究发现使用Flexwell系统对牙髓干细胞进行循环机械张力刺激(8%，0.03 Hz)第10天时可显著促进牙髓干细胞增殖。此外，据报道低强度脉冲超声产生小生物力学与细胞相互作用引起细胞内的生物效应，最终导致组织修复和再生[33]，其可以增强各种间充质干细胞包括牙髓干细胞的活力、增殖和多向分化[34-38]。GAO等[33，39]发现750 mW/cm2剂量的低强度脉冲超声明显刺激牙髓干细胞增殖，作者还发现低强度脉冲超声处理后牙髓干细胞中Piezo-1和Piezo-2蛋白水平增加，并且通过Erk1/2 MAPK信号通路参与了低强度脉冲超声介导的牙髓干细胞增殖。相反的也有文献报道[40]，模拟体内功能性咀嚼力的机械力能够通过下调黏附标记物ICAM-1和VCAM-1的表达来降低牙髓干细胞存活和黏附。 2.2 细胞力学刺激诱导牙髓干细胞成骨分化由于牙髓干细胞的增殖能力强及成骨效率高，其越来越成为当下研究骨再生中最有潜力的干细胞[41]，而细胞机械力学是影响成骨分化的重要因素[42]。研究表明在体外模拟牙齿咀嚼动作(1 Hz，3次/d，30 min/次)的机械力可以促进骨形成并限制骨吸收[43]，作者还成功研发了一种模拟咬合力的新型体外生物反应器，以促进在琼脂糖支架中的牙髓干细胞成骨分化和/或防止骨吸收。甚至有研究表明在不使用成骨诱导液的条件下，使用正畸力范围内的等轴拉伸应变力(3%应变力，连续2周)作用于牙髓干细胞，可明显增加成骨基因骨钙素和碱性磷酸酶的表达，有效诱导牙髓干细胞的成骨分化[44]。除此之外，能诱导牙髓干细胞分化的细胞力学刺激还包括脉冲流体流动[27，45]、等轴静态拉伸应变、周期性循环机械张力等。KRAFT等[27，45]研究表明脉冲流体流动可以在5 min内刺激牙髓干细胞激发一氧化氮的生成、诱导前列腺素E2的产生和环氧合酶2的表达，同时牙髓干细胞在矿化条件下连续3周受到脉冲流体流动[(0.7±0.3) Pa，5 Hz，1 h]时具有相同的反应，且成骨速度与增加的机械刺激呈正相关，提示牙髓干细胞可能在体内外矿化组织重塑过程中发挥骨样功能。此外，在0.2 Hz，10%周期机械循环张力作用下，牙髓干细胞中Ⅰ型胶原蛋白、骨涎蛋白和骨钙素等成骨相关蛋白显著增加[46]。另一项研究显示，8%周期性循环机械张力在牙髓干细胞增殖分化中也可增加骨涎蛋白和Ⅰ型胶原蛋白的mRNA表达水平，并降低α-平滑肌肌动蛋白和表面蛋白CD90的mRNA表达水平[32]。这些发现表明机械循环张力可被认为是牙髓干细胞成骨分化中的一个强有力的正向调节剂。YU等[40]研究显示5%-10%的机械张力可以促进牙髓干细胞的生存、增殖及成骨分化。还有研究显示单轴拉伸力虽然能增加牙髓干细胞的增殖，但却显著抑制其成骨分化能力[29]，而CAI等[47]研究将牙髓干细胞放置在四点弯曲循坏机械加载装置中进行2 000 με，1 Hz的单轴周期性循环拉伸力6 h，其明显抑制牙髓干细胞成骨分化，见图1。 2.3 细胞力学刺激诱导牙髓干细胞成牙本质样分化研究发现，异常的咬合力可以引起牙髓组织中的矿物质沉积及微血管系统的改变[48]，那细胞机械力是否能诱导牙髓干细胞牙源性分化，为此YU等[40]通过对牙髓干细胞进行动态静水压力处理，发现动态静水压力模拟体内条件下牙齿受到的动态牙髓内压力可以促进其牙源性分化、体外早期矿化、体内硬组织再生和骨形态发生蛋白2的表达；尽管细胞数量减少，但动态静水压力处理的牙髓干细胞表现出增强的牙源性牙本质分化能力。这些效应可能与在持续的牙髓内压作用下异位牙髓钙化的发病机制有关。此外，YANG等[28]发现循环压应力作用于牙髓干细胞12 h和24 h后牙源性相关基因牙本质基质酸性磷酸蛋白1、牙本质涎磷蛋白、碱性磷酸酶、I型胶原蛋白、骨形态发生蛋白2的表达明显上调，诱导牙髓干细胞牙源性分化。MIYASHITA等[49]探索牙髓干细胞在三维支架上通过力学刺激向牙胚分化的最佳条件，发现细胞密度为4×105/cm2，压缩力为19.6 kPa，加载时间9 h时，显著增加牙本质特异性标志物牙本质唾液磷蛋白和牙釉质溶酶蛋白的表达，诱导牙髓干细胞成牙本质样分化，但也有文献报道在一定大小、频率范围内的周期性机械压力刺激可抑制牙髓干细胞的成牙向分化，且抑制作用与周期性机械压应力大小呈正相关[50]，同时CAI 等[47]报道单轴周期性循环拉伸力亦抑制牙髓干细胞的成牙分化能力。 2.4 细胞力学刺激牙髓干细胞内的生物学转导信号通路目前，细胞的机械转导以及细胞将机械信号转化为生化反应的机制引起了人们的广泛关注[51]。牙髓干细胞的成牙细胞分化及牙根发育与Wnt信号通路和MAPK信号通路有关[52-54]，细胞力学转导至生化信号的经典途径包括MAPKs、TGF-β/Smad和Wnt/β-catenin信号级联，其中MAPK是哺乳动物细胞内广泛存在的一类丝氨酸/苏氨酸蛋白激酶，其在细胞内信号转导和基因表达方面发挥重要作用，已确定的MAPKs家族中有p38、Erk和JNK。Wnt信号通路中典型的Wnt/β-catenin可激活核内靶基因的表达。 MIYASHITA等[49]研究发现机械压缩力通过MAPK、Erk1/2和p38信号通路以及BMP-7和Wnt10a的表达来促进牙髓干细胞的分化。SHIBUTANI等[48]证明循环拉伸应变刺激诱导牙髓干细胞的成牙本质样细胞分化是由NF-E2相关转录因2(Nrf2)/HO-1途径介导的，其可能以HO-1通路为靶点，调控细胞机械应力作用下的牙源性分化。HATA等[29]研究发现单轴牵张力可以促进Akt、Erk1/2、p38 MAPK的磷酸化，并通过抑制Erk通路来消除牵张力诱导的牙髓干细胞增殖。GAO等[33]研究表明低强度脉冲超声处理后牙髓干细胞中Erk1/2被激活，且其增殖能力受到抑制，而p38和JNK未参与其中，与单轴牵张力中的Erk1/2信号通路相一致。 "

References

[1] et al. Role(s) of cytokines in pulpitis: Latest evidence and therapeutic approaches. Cytokine. 2020;126:154896.

[2] YU C, ABBOTT PV. An overview of the dental pulp: its functions and responses to injury. Aust Dent J. 2007;52 (1 Suppl):S4-16.

[3] GRONTHOS S, MANKANI M, BRAHIM J, et al. Postnatal human dental pulp stem cells (DPSCs) in vitro and in vivo. Proc Natl Acad Sci U S A. 2000;97(25):13625-13630.

[4] ALMUSHAYT A, NARAYANAN K, ZAKI AE, et al. Dentin matrix protein 1 induces cytodifferentiation of dental pulp stem cells into odontoblasts. Gene Ther. 2006;13(7):611-620.

[5] D'AQUINO R, GRAZIANO A, SAMPAOLESI M, et al. Human postnatal dental pulp cells co-differentiate into osteoblasts and endotheliocytes: a pivotal synergy leading to adult bone tissue formation. Cell Death Differ. 2007;14(6):1162-1171.

[6] ARTHUR A, RYCHKOV G, SHI S, et al. Adult human dental pulp stem cells differentiate toward functionally active neurons under appropriate environmental cues. Stem Cells. 2008;26(7):1787-1795.

[7] MARCHIONNI C, BONSI L, ALVIANO F, et al. Angiogenic potential of human dental pulp stromal (stem) cells. Int J Immunopathol Pharmacol. 2009;22(3):699-706.

[8] YANG R, CHEN M, LEE CH, et al. Clones of ectopic stem cells in the regeneration of muscle defects in vivo. PLoS One. 2010;5(10):e13547.

[9] PATIL R, KUMAR BM, LEE WJ, et al. Multilineage potential and proteomic profiling of human dental stem cells derived from a single donor. Exp Cell Res. 2014;320(1):92-107.

[10] MARRELLI M, PADUANO F, TATULLO M. Human periapical cyst-mesenchymal stem cells differentiate into neuronal cells. J Dent Res. 2015;94(6):843-852.

[11] YU J, HE H, TANG C, et al. Differentiation potential of STRO-1+ dental pulp stem cells changes during cell passaging. BMC Cell Biol. 2010;11:32.

[12] XUAN K, LI B, GUO H, et al. Deciduous autologous tooth stem cells regenerate dental pulp after implantation into injured teeth. Sci Transl Med. 2018;10(455): eaaf3227.

[13] LIZIER NF, KERKIS A, GOMES CM, et al. Scaling-up of dental pulp stem cells isolated from multiple niches. PLoS One. 2012;7(6):e39885.

[14] MITSIADIS TA, BARRANDON O, ROCHAT A, et al. Stem cell niches in mammals. Exp Cell Res. 2007;313(16):3377-3385.

[15] MITSIADIS TA, FEKI A, PAPACCIO G, et al. Dental pulp stem cells, niches, and notch signaling in tooth injury. Adv Dent Res. 2011;23(3):275-279.

[16] HOFFMAN BD, GRASHOFF C, SCHWARTZ MA. Dynamic molecular processes mediate cellular mechanotransduction. Nature. 2011;475(7356):316-323.

[17] STEWARD AJ, KELLY DJ. Mechanical regulation of mesenchymal stem cell differentiation. J Anat. 2015;227(6): 717-731.

[18] SHAH N, MORSI Y, MANASSEH R. From mechanical stimulation to biological pathways in the regulation of stem cell fate. Cell Biochem Funct. 2014;32(4):309-325.

[19] KEARNEY EM, FARRELL E, PRENDERGAST PJ, et al. Tensile strain as a regulator of mesenchymal stem cell osteogenesis. Ann Biomed Eng. 2010;38(5):1767-1779.

[20] LEONG WS, WU SC, PAL M, et al. Cyclic tensile loading regulates human mesenchymal stem cell differentiation into neuron-like phenotype. J Tissue Eng Regen Med. 2012;6 Suppl 3:s68-s79.

[21] CUI D, XIAO J, ZHOU Y, et al. Epiregulin enhances odontoblastic differentiation of dental pulp stem cells via activating MAPK signalling pathway. Cell Prolif. 2019;52(6): e12680.

[22] FAROOQ A, ZHOU MM. Structure and regulation of MAPK phosphatases. Cell Signal. 2004;16(7):769-779.

[23] YU Y, MU J, FAN Z, et al. Insulin-like growth factor 1 enhances the proliferation and osteogenic differentiation of human periodontal ligament stem cells via ERK and JNK MAPK pathways. Histochem Cell Biol. 2012;137(4):513-525.

[24] KESHET Y, SEGER R. The MAP kinase signaling cascades: a system of hundreds of components regulates a diverse array of physiological functions. Methods Mol Biol. 2010;661: 3-38.

[25] WAGNER EF, NEBREDA AR. Signal integration by JNK and p38 MAPK pathways in cancer development. Nat Rev Cancer. 2009;9(8):537-549.

[26] DOAN TKP, PARK KS, KIM HK,et al. Inhibition of JNK and ERK Pathways by SP600125-and U0126-Enhanced Osteogenic Differentiation of Bone Marrow Stromal Cells. Tissue Engineering and Regenerative Medicine.2012;9: 283-294.

[27] KRAFT DC, BINDSLEV DA, MELSEN B, et al. Human dental pulp cells exhibit bone cell-like responsiveness to fluid shear stress. Cytotherapy. 2011;13(2):214-226.

[28] YANG H, SHU YX, WANG LY, et al. Effect of cyclic uniaxial compressive stress on human dental pulp cells in vitro. Connect Tissue Res. 2018;59(3):255-262.

[29] HATA M, NARUSE K, OZAWA S, et al. Mechanical stretch increases the proliferation while inhibiting the osteogenic differentiation in dental pulp stem cells. Tissue Eng Part A. 2013;19(5-6):625-633.

[30] PAPHANGKORAKIT J, OSBORN JW. The effect of normal occlusal forces on fluid movement through human dentine in vitro. Arch Oral Biol. 2000;45(12):1033-1041.

[31] YASHIRO K, YAMAUCHI T, FUJII M, et al. Smoothness of human jaw movement during chewing. J Dent Res. 1999; 78(10):1662-1668.

[32] HAN MJ, SEO YK, YOON HH, et al. Effect of mechanical tension on the human dental pulp cells. Biotechnology and Bioprocess Engineering.2008;13(4):410-417.

[33] GAO Q, WALMSLEY AD, COOPER PR, et al. Ultrasound Stimulation of Different Dental Stem Cell Populations: Role of Mitogen-activated Protein Kinase Signaling. J Endod. 2016; 42(3):425-431.

[34] CUI JH, PARK K, PARK SR, et al. Effects of low-intensity ultrasound on chondrogenic differentiation of mesenchymal stem cells embedded in polyglycolic acid: an in vivo study. Tissue Eng. 2006;12(1):75-82.

[35] LEE HJ, CHOI BH, MIN BH, et al. Low-intensity ultrasound stimulation enhances chondrogenic differentiation in alginate culture of mesenchymal stem cells. Artif Organs. 2006;30(9): 707-715.

[36] WANG YK, CHEN CS. Cell adhesion and mechanical stimulation in the regulation of mesenchymal stem cell differentiation. J Cell Mol Med. 2013;17(7):823-832.

[37] HU B, ZHANG Y, ZHOU J, et al. Low-intensity pulsed ultrasound stimulation facilitates osteogenic differentiation of human periodontal ligament cells. PLoS One. 2014;9(4): e95168.

[38] MARVEL S, OKRASINSKI S, BERNACKI SH, et al. The development and validation of a LIPUS system with preliminary observations of ultrasonic effects on human adult stem cells. IEEE Trans Ultrason Ferroelectr Freq Control. 2010;57(9):1977-1984.

[39] GAO Q, COOPER PR, WALMSLEY AD, et al. Role of Piezo Channels in Ultrasound-stimulated Dental Stem Cells. J Endod. 2017;43(7):1130-1136.

[40] YU V, DAMEK-POPRAWA M, NICOLL SB, et al. Dynamic hydrostatic pressure promotes differentiation of human dental pulp stem cells. Biochem Biophys Res Commun. 2009;386(4): 661-665.

[41] GRAZIANO A, D'AQUINO R, LAINO G, et al. Dental pulp stem cells: a promising tool for bone regeneration. Stem Cell Rev. 2008;4(1):21-26.

[42] CHEN X, GUO J, YUAN Y, et al. Cyclic compression stimulates osteoblast differentiation via activation of the Wnt/β-catenin signaling pathway. Mol Med Rep. 2017;15(5): 2890-2896.

[43] JI J, SUN W, WANG W, et al. The effect of mechanical loading on osteogenesis of human dental pulp stromal cells in a novel in vitro model. Cell Tissue Res. 2014;358(1):123-133.

[44] TABATABAEI FS, JAZAYERI M, GHAHARI P, et al. Effects of equiaxial strain on the differentiation of dental pulp stem cells without using biochemical reagents. Mol Cell Biomech. 2014; 11(3):209-220.

[45] KRAFT DC, BINDSLEV DA, MELSEN B, et al. Mechanosensitivity of dental pulp stem cells is related to their osteogenic maturity. Eur J Oral Sci. 2010;118(1):29-38.

[46] HAN MJ, SEO YK, YOON HH, et al. Upregulation of bone-like extracellular matrix expression in human dental pulp stem cells by mechanical strain. Biotechnology and Bioprocess Engineering. 2010;15(4):572-579.

[47] CAI X, ZHANG Y, YANG X, et al. Uniaxial cyclic tensile stretch inhibits osteogenic and odontogenic differentiation of human dental pulp stem cells. J Tissue Eng Regen Med. 2011;5(5): 347-353.

[48] SHIBUTANI N, HOSOMICHI J, ISHIDA Y, et al. Influence of occlusal stimuli on the microvasculature in rat dental pulp. Angle Orthod. 2010;80(2):316-321.

[49] MIYASHITA S, AHMED NE, MURAKAMI M, et al. Mechanical forces induce odontoblastic differentiation of mesenchymal stem cells on three-dimensional biomimetic scaffolds. J Tissue Eng Regen Med. 2017;11(2):434-446.

[50] 肖敏,陈博,李明伟,等.机械压应力刺激对人牙髓干细胞体外增殖矿化的影响[J].牙体牙髓牙周病学杂志,2015,25(4):187-192.

[51] DADO D, SAGI M, LEVENBERG S, et al. Mechanical control of stem cell differentiation. Regen Med. 2012;7(1):101-116.

[52] YAMASHIRO T, ZHENG L, SHITAKU Y, et al. Wnt10a regulates dentin sialophosphoprotein mRNA expression and possibly links odontoblast differentiation and tooth morphogenesis. Differentiation. 2007;75(5):452-462.

[53] 何梅,吴家媛.Wnt/β-catenin信号通路对牙根发育的影响[J].中国组织工程研究,2017,21(28):4556-4562.

[54] ZHANG H, LIU S, ZHOU Y, et al. Natural mineralized scaffolds promote the dentinogenic potential of dental pulp stem cells via the mitogen-activated protein kinase signaling pathway. Tissue Eng Part A. 2012;18(7-8):677-691.

[55] SHI S, ROBEY PG, GRONTHOS S. Comparison of human dental pulp and bone marrow stromal stem cells by cDNA microarray analysis. Bone. 2001;29(6):532-539.

[56] LEE SK, LEE CY, KOOK YA, et al. Mechanical stress promotes odontoblastic differentiation via the heme oxygenase-1 pathway in human dental pulp cell line. Life Sci. 2010;86(3-4):107-114.