The mechanism of red cell (dis)aggregation investigated by means of direct cell manipulation using multiple optical trapping

Abstract

Summary. We used multiple optical trapping to study the mechanism of red cell (dis)aggregation. Two sets of optical 'tweezers' were used to bring two red blood cells together to form a two-cell aggregate and then to pull them apart, to study the interaction between the cells.We found that cross-bridging occurred in normal reversible aggregation as we observed binding and the occurrence of small tethers between opposite cell membranes. Furthermore, the cells could only be parted by sliding them side by side with a maximum velocity in the order of mm/s indicating accumulation of the cross-bridges.

Normal and system lupus erythematosus red blood cell interactions studied by double trap optical tweezers: direct measurements of aggregation forces

“…13,14 Recent development of optical tweezers has led to the widespread dissemination of this technique in biomedical research due to the ability to trap and manipulate single objects at cellular and subcellular level. [15][16][17][18] This technique is finding an increasing application in study of the elastic properties of individual RBCs, which determine the ability to withstand large deformations while passing through small capillaries. Recently, qualitative measurements of RBC properties such as membrane viscosity, adhesion and zeta potential have been performed at individual cells utilizing double optical tweezers.…”

Orientation of Red Blood Cells and Rouleaux Disaggregation in Interference Laser Fields

“…The other component F ⊥ of the gradient force is directed along the aggregate axis and acts as a stretching or compressive force dependent on the cell position in the rouleau and in the interference fringes. As is known [19], a much stronger force is needed to decompose the aggregated RBC in a stretching direction so the contribution of the force component F ⊥ to disaggregation of the rouleau is hardly of any significance.…”

“…It is known [19] that sliding cells side by side easily disrupts the contact between aggregated RBCs. In the case of trapping the regular linear rouleau into the interference maximum (as shown on Figure 5(a)), gradient forces act perpendicular to and towards the rouleau axis.…”

Elliptical optical tweezers for trapping a red blood cell aggregate

“…Although theoretical information is available concerning light-matter interaction at the single RBC aggregate level [16], tools for single-cell studies are still under development. Some papers describe the optical trapping and manipulation of RBC aggregates using two * E-mail: matti.kinnunen@ee.oulu.fi point optical tweezers to study the RBC (dis)aggregation mechanism and to measure the present aggregation forces [17], [18]. Also laser interference patterns have been used to study the orientation and disaggregation of RCBs [19].…”

“…2 is not as sharp as in some other papers [18] employing a thin sample cuvette and an objective with a much shorter working distance. While two-point tweezers allow forming and pulling down aggregates and measuring forces between cells [17], [18], they cannot be used to move and lift long aggregates.…”