© 2003 Robert A. Freitas Jr. All Rights Reserved.

Robert A. Freitas Jr., Nanomedicine, Volume IIA: Biocompatibility, Landes Bioscience, Georgetown, TX, 2003

15.5.4 Mechanocompatibility with Extracellular Matrix and Tissue Cells

Nanomedical systems interact with components of the extracellular matrix or ECM (Section 9.4.4.2) primarily in two circumstances. First, during histonatation (Section 9.4.4) nanorobots traversing the ECM will apply nondestructive forces to ECM fibers as a consequence of locomotion. Second, traversing tightly-packed cell-rich tissues or performing macroscale surgical procedures may require the dissection, and later the reconnection, of ECM fibrous components by nanomedical systems. This is important because simple detachment of tissue cells from all contacts with the ECM [3964] and the physical manipulation of cell shape [3965] have been shown to induce apoptosis (Section 10.4.1.1) experimentally, and mechanosensitive channels may also modulate cell migration [3792]. However, R. Smigrodzki notes that a rather extreme damage to the ECM would be needed to induce apoptosis – e.g., “probably mere traversing of tissue by nanorobots would not be sufficient to cause it.” The mechanocompatibility of nanofibers and stationkeeping nanorobots embedded in human tissue was briefly discussed in Sections 6.4.3.6 and 7.3.3.

Our brief discussion considers first the force threshold for biological response from cells whose physical connections to the ECM are mechanically disrupted (Section 15.5.4.1), and the known diseases involving mechanical damage to the ECM that such disruption might mimic (Section 15.5.4.2). Finally, we consider the size and force threshold for perceptible sensation to the patient, during nanorobot histonatation (Section 15.5.4.3). Many other fascinating but highly specialized mechanocompatibility issues are ignored here, as for example the role of mechanical fluid flows (such as might be generated by micromechanical or nanomechanical devices) in the generation of left-right asymmetry during the development of vertebrate embryos [6218].

Last updated on 30 April 2004