International Application Number: PCT/ZA2013/000019
Transport of cells in liquid nitrogen or a dry shipper is expensive and requires specialized, expensive and risky procedures. Recovery of cells is not easy, immediate or reproducible. Phoenix Therapeutics has a patent pending on a device which permits airmail of stem cells from the point of production directly to the point of care, use or storage. Cells that may be transported include adult stem cells, embryonic stem cells, progenitor stem cells, hematopoietic stem cells and other living cells.
This will impact stem cell research and facilitate a more immediate point-of care use of stem cells in the clinic using a robust, fast, safe and inexpensive way of transporting living cells. Recoveries are over 90% viable cells. The cost of this robust package for the airmail distribution of cells will be less than 1% of the cost of using a dry shipper.
The cells in the inner bag of the patent pending transport package exist within a thin film of medium within the pores of a biocompatible, biodegradeable alginate hydrogel. The hydrogel is transported in a petri dish within a sterile, sealed inner breatheable bag. Everything is assembled and sterilized by gamma irradiation before the addition of the cells for transport. The inner bag permits exchange of gases but retains water vapour. Cells therefore do not dehydrate and die. The medium in which the cells are transported contains penicillin and streptomycin but no fetal calf serum, which maintains cells in suspension culture. The medium contains phosphate buffer which maintains medium pH when cells are in contact with air.
Although the adsorbed cells are in suspension culture and grow very little, they will release carbon dioxide. Any carbon dioxide is specifically and rapidly released from the inner bag and oxygen is also transported but to a more limited degree. The inner bag is enclosed in a laminated bubble bag made from polyethylene on the inside and aluminium foil on the outside. This forms a bubble wrap on the inside of the larger outer bag. The air in the bubbles on the inside of the laminate act as a lung for the cells in the inner bag as polyethylene is permeable to oxygen. The bubbles also cushion and protect the enclosed perti dish with its living cells, and buffer heat exchange with the external environment by limiting heat conduction. The aluminium foil outside of the laminate buffers heat exchange through reflection. The dynamic environment within the inner bag ensures optimal cell survival and minimum change in the cells during transport. The package is extremely light and inexpensive to post by airmail.
Recovery of cells from the alginate scaffold is simple and does no damage to the adsorbed cells. The 3-D alginate scaffold is broken down using tri-sodium citrate which complexes the calcium ions which ensure cross-linking between alginate strands and the structural integrity of the hydrogel. The cells exist in a thin layer of medium within the hydrogel and are undamaged and released by this digestion. They may then be washed in PBS and recovered in a centrifuge.
Attached below is a diagram which explains the patent application.