1 Cell migration at biointerfaces Dr. Prabhas Moghe Biointerfacial Characterization 125:583 September 18, 2006

2 Outline Importance of Cell Migration Modes of cell migration Cell migration and cell adhesion Methods to quantify cell migration Cell migration on dynamic biointerfaces

3 Significance of studying cell motility Cell motility is key to: –Wound healing/repair (quality and kinetics) –Tissue adhesion and turnover on implanted materials –Cancer invasiveness/metastasis –Sorting of cells during development/embryogenesis –White blood and immune cell functions –

4 Modes of Cell Migration - A Primer (a) Random Motility: No orientation bias is exhibited with respect to S or P. (b) Topotaxis: Biased turning toward gradient direction (shown toward right) (c) Orthotaxis: Enhanced S when the cell is oriented in the gradient direction, (d): Klinotaxis: Decreased P when the cell is oriented in the gradient direction (e): Orthokinesis: S decreases with increasing stimulus concentration (f) Klinokinesis: P increases with increasing stimulus concentration S: Cell Speed P: Directional Persistence Simplest Classification: Random Motility versus Chemotaxis

5 Cell Migration Indirect Methods Under-Agarose Assay Membrane Infiltration Assay (Millipore/Boyden) 3-D Conjoined Gel Assay Orientation Assay (Zigmond)

6 Cell Migration Assays Filter Assay Under-Agarose Assay Conjoined Gel Assay

7 Molecular View of Cell Adhesion

8 Strength of Adhesion & Receptor-Ligand Affinity Kuo SC. Lauffenburger DA. Relationship between receptor/ligand binding affinity and adhesion strength. [Journal Article] Biophysical Journal. 65(5): , 1993 Nov.

9 Relation between cell adhesion and cell migration DiMilla et al., JCB, 1992

10 Cell migration & cell adhesive strength Palecek et al., Nature 385:537 (1997)

11 3-D Cell migration Biophys J Aug;89(2): Epub 2005 May 20.

12 Cell Migration Analysis on Biomaterials: Direct Methods Biophys J Mar;72(3): Biophys J Feb;61(2):

13 Direct Migration Methods, Contd.

14 Theory of Cell Migration: Indirect Assays Cell Population Migration is described in terms of objective migratory parameters, , and . These parameters do not vary with system size, time of incubation, etc.  = random motility coefficient (cm 2 /s)  = chemotaxis coefficient (cm 2 /s-M) Two fundamental equations are required: - Cell transport equation (captures migration behavior) - Cell conservation equation

15 Theory of Cell Migration Cell Migration in an Isotropic Environment (Random Migration): where c is the cell density and a is the concentration of soluble stimulant concentration (if any). Cell conservation equation: Overall equation:

16 Solution to Cell Migration Model time, t CoCo x Solution: If C(x,t) where (Note, erf(0)=0; erf( )=1)

17 Example of  variation with biomaterial substrate Chang, C., Lieberman, S., and Moghe, P.V., J. Mat. Sci. Mat. Med. 11: 337 (2000) Human Neutrophils on ePTFE, a vascular prosthetic material, treated with different plasma proteins, and in the presence of the chemoattractant, formyl-methionyl-leucyl- phenylalanine (fMLP).

18 Protein interface on biomaterials shifts the directional motility of cells Chang, C., Lieberman, S., and Moghe, P.V., J. Mat. Sci. Mat. Med. 11: 337 (2000)

19 Cell migration on anisotropic substrates Cell migration under flow Cell migration on oriented textured substrates Cell migration on substrates with chemical, electrical, stiffness gradients.

20 Analysis of Cell Motility on Biosubstrates under Flow Rosenson-Schloss et al, J. Biomed. Mater. Res., 60:8, 2002 ’

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23 Quantitation of Cell Migration under Flow

24 Cell migration on dynamic biointerfaces (ligand-nanoparticles) Tjia and Moghe, Tissue Eng, 8: 247 (2002); Annals of Biomed. Eng, 30: 851 (2002)

25 Cell motility behavior characterization as a function of ligand-microparticle density (Tjia and Moghe, Tissue Eng., 2002)

26 Cell motility behavior characterization, continued

27 Mathematical description of cell motility and ligand binding (Tjia & Moghe, ABE, 2002)

28 Kinetics of ligand binding and internalization within motile cells

29 Cell motility correlates with matrix ligand sampling