All-in-one processing of heterogeneous human cell grafts for gene and cell therapy

Abstract

Current cell processing technologies for gene and cell therapies are often slow, expensive, labor intensive and are compromised by high cell losses and poor selectivity thus limiting the efficacy and availability of clinical cell therapies. We employ cell-specific on-demand mechanical intracellular impact from laser pulse-activated plasmonic nanobubbles (PNB) to process heterogeneous human cell grafts ex vivo with dual simultaneous functionality, the high cell type specificity, efficacy and processing rate for transfection of target CD3+ cells and elimination of subsets of unwanted CD25+ cells. The developed bulk flow PNB system selectively processed human cells at a rate of up to 100 million cell/minute, providing simultaneous transfection of CD3+ cells with the therapeutic gene (FKBP12(V36)-p30Caspase9) with the efficacy of 77% and viability 95% (versus 12 and 60%, respectively, for standard electroporation) and elimination of CD25+ cells with 99% efficacy. PNB flow technology can unite and replace several methodologies in an all-in-one universal ex vivo simultaneous procedure to precisely and rapidly prepare a cell graft for therapy. PNB's can process various cell systems including cord blood, stem cells, and bone marrow.

Figure 1

Principle of simultaneous plasmonic nanobubble (PNB) treatment with PNBs of different sizes. (a) selective transfection of CD3+ cells (blue) under excitation of 532 nm laser pulse, (b) selective destruction of CD25+ cells (brown) under excitation of 1,064 nm laser pulse. (c) Diagram of the flow system with the two spatially-separated laser beams, 532 and 1,064 nm, aligned to expose flowing cells in the cuvette, and (d) photo of the flow cuvette with the transparent channel of 5 × 0.8 mm cross-section installed for the laser treatment.

Figure 2

Cell type-specific generation of plasmonic nanobubbles (PNBs). (a) Plasmonic nanobubble (PNB) lifetime as function of the laser pulse fluence in CD25-positive (red) and CD3-positive (black) individual cells (CD25 cells were treated with NS240-CD25 gold conjugates and 1,064 nm laser pulse; CD3 cells were treated with NSP60-CD3 gold cinjugates and 532 nm laser pulse). Insets show typical time-responses of PNBs in CD25-positive (red) and CD3-positive (black) cells. (b) PNB lifetime in cells as a function of the laser pulse wavelength (laser pulse fluence 65 mJ/cm²) and of the incubation conditions: blue—CD3-positive cells treated by NSP60-CD3 gold conjugates, red—CD3-positive cells treated by NS240-CD25 gold conjugates, green—CD25-positive cells treated by NS240-CD25 gold conjugates (50–100 cells were individually measured for each data point).

Figure 3

PNB-induced destruction of CD25-positive cells. Bright-filed image of CD25-positive cell before (a) and after (b) plasmonic nanobubble treatment with a single laser pulse (1,064 nm, 65 mJ/cm²). (c) The effective viability of CD25-positive cells viability as a function of the laser pulse fluence in 10 minutes after cell processing. Scale bar: 5 µm.

Figure 4

PNB-induced injection of molecular cargo to CD3-positive cells. Dependence of the Dextran injection efficacy (green) and the effective cell viability (red) of CD3-positive cells as function of the laser pulse fluence. Insert show the typical fluorescent images of the cells before (left) and after (right, top) the PNB treatment. The effective cell viability was measured 10 minutes after the PNB treatment.

Figure 5

Transfection of CD3-positive cells with therapeutic gene. The transfection efficacy (percentage of green fluorescence-positive cells) of CD3-positive cells with the therapeutic gene FKBP12(V36)-p30Caspase9 as a function of: (a) time and the effective cell viability after the plasmonic nanobubble (PNB) generation (insets show typical fluorescent images of cells 24 (left corner) and 96 (right top corner) hours after the PNB generation), (b) plasmid concentration (72 hours after the PNB generation), and (c) PNB lifetime (green, measured 72 hours after the PNB generation), red: the effective cell viability of PNB-treated cells 72 hours after the treatment (100–150 cells were measured for each data point).