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1、ARTICLESDynamicsofcellorientationRUMIDE1,ASSAFZEMEL1,2ANDSAMUELA.SAFRAN1*1DepartmentofMaterialsandInterfaces,WeizmannInstituteofScience,Rehovot76100,Israel2DepartmentofNeurobiology,PhysiologyandBehavior,UniversityofCalifornia,Davis,California95616,USA*e-mail:sam.safran@weizmann.ac.ilPu
2、blishedonline:29July2007;doi:10.1038/nphys680Manyphysiologicalprocessesdependontheresponseofbiologicalcellstomechanicalforcesgeneratedbythecontractileactivityofthecellorbyexternalstresses.Usingasimpletheoreticalmodelthatincludestheforcesduetoboththemechanosensitivityofcellsandtheelasti
3、cityofthematrix,wepredictthedynamicsandorientationofcellsinboththeabsenceandpresenceofappliedstresses.Themodelpredictsmanyfeaturesobservedinmeasurementsofcellularforcesandorientationincludingtheincreasewithtimeofthecellularforcesintheabsenceofappliedstressandtheconsequentdecreaseofthef
4、orceinthepresenceofquasi-staticstresses.Wealsoexplainthepuzzlingobservationofparallelalignmentofcellsforstaticandquasi-staticstressesandofnearlyperpendicularalignmentfordynamicallyvaryingstresses.Inaddition,wepredicttheresponseofthecellularorientationtoasinusoidallyvaryingappliedstress
5、asafunctionoffrequency.Understandingtheactiveresponseofbiologicalcellstomechanicalthefocaladhesions.Here,themagnitudeofthedipolestrength−11forcesisimportantfortherationaldesignofartificialtissues,forcontractiondipolesP<0istypically'10J(ref.21).Inourcellularself-assembly,musclegrowth,wou
6、ndhealingandmodel,forsimplicity,wefocusonneedle-likecells(forexample,1–5angiogenesis.Experimentsontissuecells,includingfibroblasts,musclecellsandoftenfibroblastsexhibitbipolarmorphologies)forsmooth-musclecells,endothelialcellsandstemcellshaveshownwhichtheforce,f,andthevectorconnectingthe
7、focaladhesions,thatthesecellsactivelysensethemechanicalpropertiesofl,arebothinthedirectionofthecellaxis.Weshalltakethetheirenvironmentandrespondtothestressinthematrixbyinstantaneousalignmentofaneedle-likecelltobeinthezdirectionremodellingtheactincytoskeletonandothercellularprocesses.
