| abstract |
A material capable of forming hydrogen bonds or covalent bonds with loading materials incorporated in loaded cells is introduced into the cells with the loading materials to inhibit the destruction of the cell membranes by the loading material after the permeability of the membranes is brought back down to its normal value. In order to provide for the hydrogen bond formation with common loading materials, such as methotrexate, proteins such as albumin and sugars such as sucrose are effective. The time period during which these materials inhibit a destructive effect on the membranes of loaded cells is well defined. Accordingly, when cells are loaded with a medicament for interaction with substances external to the cells in a physiological solution in which they are placed, which materials have no destructive effect on the cell membranes, it is advantageous to load the cells also with a material having such a destructive effect, such as pronase P, and at the same with a sugar or a protein for delaying its effect, so that the medicament will be released by destruction of the cell membranes after a predetermined time. In this manner, by injection into an animal bloodstream of a suspension of loaded cells prepared according to the invention suspended in a physiological solution, the timing of the release of a medicament into the bloodstream can be controlled. |