Retinoblastoma is a retinal cancerous disease that primarily affects young children. To date, preservation of the eye and its functionality is secondary to saving the child’s life. EpCAM+ Y79 retinoblastoma cells behave like cancer stem cells that are recognized as cells that are resistant to treatment. Additionally, reoccurrence of tumours is attributed to the persistence of cancer stem cells. An effective technique to treat retinoblastoma cancer cells is demonstrated using femtosecond laser pulses and EpCAM targeting gold nanorods (Au-NRs). Both fluorescence viability assay and MTS cellular metabolism assay confirm an astonishing cellular viability drop, to ~10%. It is shown that right after laser irradiation the cellular membrane ruptures. FESEM imaging shows that Au-NRs reach melting temperature after laser pulse exposure. The medium of the eye is transparent to NIR laser irradiation, making this treatment ideal for this type of cancer. This treatment methodology would also be an invaluable tool for treatment of chemotherapy-resistant and radiation-resistant cancers.
The mechanism of femtosecond laser nanosurgical attachment is investigated in the following article. Using sub-10 femtosecond laser pulses with 800 nm central wavelength were used to attach retinoblastoma cells. During the attachment process the cell membrane phospholipid bilayers hemifuse into one shared phospholipid bilayer, at the location of attachment. Transmission electron microscopy was used in order to verify the above hypothesis. Based on the imaging results, it was concluded that the two cell membrane coalesce to form one single shared membrane. The technique of cell-cell attachment via femtosecond laser pulses could potentially serve as a platform for precise cell membrane manipulation. Manipulation of the cellular membrane is valuable for studying diseases such as cancer; where the expression level of plasma proteins on the cell membrane is altered.
Attachment of single cells via hemifusion of cellular membranes using femtosecond laser pulses is reported in this manuscript. This is a method to attach single cells using sub-10 femtosecond laser pulses, with 800 nm central wavelength delivered from a Ti:Sapphire laser is described. A fluorescent dye, Calcein AM, was used to verify that the cell’s cytoplasm did not migrate from a dyed cell to a non-dyed cell, in order to ascertain that the cells did not go through cell-fusion process. An optical tweezer was used in order to assess the mechanical integrity of the attached joint membranes. Hemifusion of cellular membranes was successful without initiating full cell fusion. Attachment efficiency of 95% was achieved, while the cells’ viability was preserved. The attachment was performed via the delivery of one to two trains of sub-10 femtosecond laser pulses lasting 15 milliseconds each. An ultrafast reversible destabilization of the phospholipid molecules in the cellular membranes was induced due to a laser-induced ionization process. The inner phospholipid cell membrane remained intact during the attachment procedure, and cells’ cytoplasm remained isolated from the surrounding medium. The unbounded inner phospholipid molecules bonded to the nearest free phospholipid molecule, forming a joint cellular membrane at the connection point. The cellular membrane hemifusion technique can potentially provide a platform for the creation of engineered tissue and cell cultures.