Evaluation of Novel Stereotactic Cannula for Stem Cell Transplantation against Central Nervous System Disease

Cell therapy for central nervous system (CNS) disorders is beginning to prove its safety and efficiency. Intraparenchymal transplantation can be an option for cell delivery; however, one concern regarding this method is that the transplantation cannula may cause additional brain injuries. These include vessel damage, which results in brain hemorrhage, and clogging of the cannula by brain debris and/or cell clusters, which requires replacement of the cannula or forced injection causing jet flow of the cell suspension. We compared cannulas for cell delivery used in clinical trials, the Pittsburg and Mizuho cannulas, to a newly designed one, MK01, to assess their usability. MK01 has a spherical-shaped tip with a fan-like open orifice on the side of the cannula, which prevents vessel damage, clogging of brain debris, and jet flow phenomenon. We compared the extent of rat cervical and abdominal arterial damage with the cannula, the amount of debris in the cannula, the force needed to cause jet flow, and cell viability. While the viability of cells passed through the cannulas was almost the same among cannulas (approximately 95%), the Pittsburg cannula caused cervical arterial injury and subsequent hemorrhage, as it required a significantly smaller force to penetrate the arterial wall. Moreover, the Pittsburg cannula, but not the Mizuho and MK01 cannulas, showed high frequency of brain debris in the needle tip (approximately 80%) after brain puncture. While jet flow of the injection liquid was observed even when using smaller forces in the Pittsburg and Mizuho cannulas, MK01 constantly showed low jet flow occurrence. Thus, MK01 seems to be safer than the previously reported cannulas, although further investigation is necessary to validate its safety for clinical use.

An account of some experiments exhibiting new instances of the absorbing power of streams; with a few remarks on the pulsation of jets

The experiments of which an account is given in this paper illustrate the absorbing power of a stream of fluid, whether issuing from the open orifice of a reservoir, or flowing through rigid tubes. The effects of this power are seen in the position of the fluid contained in a vertical tube open at both ends, placed within the reservoir, and of which one end is brought within the influence of the effluent stream; and also, when one end of a bent tube is brought into the stream issuing from the open orifice of a reservoir, while the other end is immersed in a coloured fluid. The author accounts for the intermitting or pulsatory character of the jet issuing from an open horizontal pipe, having a small hole on the upper side, by the introduction of air, which, accumulating from time to time, forms a bubble, which when it has attained a certain size, occasions an obstruction to the free passage of the liquid, until the obstacle is overcome by increased pressure from behind, and the jet then resumes its former velocity. These changes occurring periodically, give rise to the appearance of pulsation which is observed in these circumstances.