Cilia-driven flow fields for transport and selective capture of bacteria

Transcription

1 Cilia-driven flow fields for transport and selective capture of bacteria 0.1mm Janna Nawroth, Ph.D. Wyss Institute for Biologically Inspired Engineering, Harvard University Active Matter Kavli Institute for Theoretical Physics May 15 th,

2 Traditional drug development Time: 10 years Cost: $1 Billion/drug 2

3 Traditional drug development Time: 10 years Cost: $1 Billion/drug Reasons for drug failure: poor translation between test platforms and humans 3

4 The quest for a better in-vitro model of human disease and drug response Organ-on-a-chip 3-D microfluidic cell culture chip from human cells simulates characteristic mechanics and physiological responses of entire organs human platform for drug testing and disease models Example: lung-blood barrier function Duh et al. 2010, Science, Reconstituting Organ-Level Lung Functions on a Chip 4

5 Organ-on-a-chip design Biology Identify relevant structure-function relationships Structure and motion of building blocks (cells, matrix) Engineering Design, build and test structure-function relationships Emergent functions Quantitative metrics of organ fitness 5

6 Organ-on-a-chip design Biology Identify relevant structure-function relationships Structure and motion of building blocks (cells, matrix) Engineering Design, build and test structure-function relationships Emergent functions Quantitative metrics of organ fitness Example lung chip Metrics of fitness are Structural integrity Absorption air blood 6

7 2 case studies Muscle-powered fluid transport relevant to cardiovascular system Cilia-powered fluid transport relevant to respiratory organs, brain, Fallopian tube with John Dabiri (Caltech) Kit Parker (Harvard) Donald Ingber (Harvard) with Eva Kanso (USC) Margaret McFall-Ngai (UW Madison) Edward Ruby (UW Madison) John Dabiri (Caltech) Scott Fraser (USC) 7

8 Case study: human heart Heart Function 8

9 Case study: human heart Heart Function Body-fluid interaction Tissue geometry + Kinematics + Microstructure 9

10 A simplified heart: jellyfish 10

11 A simplified heart: jellyfish Jellyfish Function Body-fluid interaction Tissue geometry + Kinematics + Microstructure 11

12 Measuring jellyfish fitness Jellyfish function Feeding flux Propulsion Fluid transport + + Muscle fiber alignment Contraction kinematics Bell geometry 12

13 Muscle fiber alignment Anisotropic muscle layout Muscle fibers (F-actin, green) 5/21/ µm 13

14 Muscle fiber alignment Micropattern Anisotropic muscle layout Stamp 40µm 14

15 Muscle fiber alignment Jellyfish Engineered 15

16 Bell kinematics 16

17 Bell kinematics Muscle-elastomer composite 17

18 Bell kinematics Muscle-silicone 18

19 Body geometry Feitl, 2009; Nawroth,

20 Body geometry Feitl, 2009; Nawroth,

21 21

22 Real and artificial jellyfish propulsion Control: Jellyfish Optimal design Suboptimal design 22

23 Quantifying feeding and propulsion currents 23

24 Control: Flow field in jellyfish 24

25 Flow field in optimal Medusoid 25

26 Fitness metrics Nawroth JC et al. (2012) A tissue-engineered jellyfish with biomimetic propulsion 26

27 Heart-on-a-chip: further reduction Microstructure Tissue contractile stress Ref: A. Agarwal et al,

28 Case study: ciliated epithelium e.g., respiratory epithelium 28

29 Case study: ciliated epithelium e.g., respiratory epithelium 29

30 Cilia-powered fluid transport Ciliated epithelium (Paramecium) 10um Bulk flow profile 30

31 Cilia-powered fluid transport Ciliated epithelium (Paramecium) 10um Particle capture & clearance Transport of fluids, solutes and cells 31

32 Structure-function relationships of ciliated surfaces Cilia fitness Selective bacterial recruitment 32

33 Structure-function relationships of ciliated surfaces Cilia fitness Selective bacterial recruitment Fluid transport and mixing Surface geometry + Metachronal wave +?? Ciliary structure and kinematics 33

34 A master of selective bacterial recruitment: The Hawaiian bobtail squid Internal ciliated organ captures 1 µm bacteria species (Vibrio fischeri) from huge microbial background (0.5%), and wide range of particle sizes Retention efficiency in typical ciliary filter feeders #/ml Particle size distribution in coastal waters Jorgensen, 1994 Largest dimension in µm Reynolds et al.,

35 The squid ciliated organ 35

36 The light organ is subject low Reynolds number flow Light organ in mantle flow Ciliary flow of isolated light organ Eye Horns Light organ 1mm 100 µm UD Re 0.2 UD Re

37 The mucociliary trap Mucus aggregation 37

38 Red: cilia Green: Vibrio fischeri The mucociliary trap: not such a good trap? 10 7 particles/ml 50µm L U R Encounter model for passive cylinder in flow (Humphries, PNAS, 2009) Capture rate similar to predicted encounter rate of passive cylinder in flow No obvious increase in capture rate compared to chance 38

39 The mucociliary trap - not for everyone: Evidence for size-biased capture 1µm (blue), 2µm (green), 4µm (orange); 10 7 particles/ml each Red: cilia 100µm 39

40 Cilia-generated flow field 1 µm particles 100 µm 40

41 Cilia-generated flow field Particle path lines 41

42 Cilia-generated hydrodynamic sieve Particle tracking Ratio advected particles:captured particles 50:1 42

43 In vivo capture Appendages 4um 1um 50um 43

44 In vivo capture 4um 1um 44

45 Current work: Identifying structure-function relationships Cilia fitness Capture and aggregation of bacteria (-sized particles) Fluid transport and mixing + + Ciliary structure and kinematics Metachronal wave Surface geometry 45

46 Current work: Identifying structure-function relationships using a variety of methods and approaches 46