Shipment of human islets for transplantation

The use of regional human islet cell processing centers (ICPC) supporting distant clinical islet transplantation programs (CITP) has proven successful in recent clinical trials. Standardization of islet shipping protocols is needed to preserve cell product identity, quantity, quality and sterility, and to meet criteria for transplantation. We evaluated the use of gas-permeable bags for human islet preparation shipment from a single ICPC to two remote CITPs. Product release tests (counts, purity, viability, sterility and potency) were performed at both centers using identical protocols to determine adequacy for transplantation.Thirty-five islet preparations were shipped either immediately after isolation (n = 20) or following culture (n = 15). Islet recovery rate after shipment was higher in cultured preparations, when compared to those not cultured (91.2 +/- 4.9% vs. 72.9 +/- 4.7%, respectively; p < 0.05), though the overall recovery rate based on isolation and pre-transplant counts was comparable (72.9 +/- 4.7% vs. 70.4 +/- 3.5%, respectively; p = N.S.). All preparations met product release criteria for transplantation. Additional experiments showed that gas-permeable bags led to improved recovery and potency, when compared to 50-mL conical tubes or to non-gas-permeable bags for shipment.Collectively, our data demonstrate that the use of gas-permeable bags is efficient for clinical-grade and should be preferred also for the shipment of research-grade islet preparations.

A comparison of OPO pulsatile machine preservation practices and results

CONTEXT

Kidney preservation has been performed by either ice (static) or machine pulsatile perfusion. Ice storage is simple, with only 1 methodology. Machine perfusion, on the other hand, is accomplished using multiple methodologies. This article delineates the different methodologies of pumping centers throughout the country.

OBJECTIVE

Pulsatile machine perfusion is again being viewed as the preservation method of choice for kidneys from non-heart-beating cadaver donors and cadaver kidneys from marginal donors. To develop indices to predict the viability of cadaver kidneys for transplant, a review of the organ procurement organizations, specific perfusion techniques, and a comparison of the delayed graft function and graft survival rates were considered.

METHODS

A survey, asking for specifics on perfusion parameters, pulsatile machine perfusion experience, and criteria for perfusion implementation and graft survival results, was mailed to all organ procurement organizations in the United States.

RESULTS

Of the 44 centers that responded to the survey, 12 used pulsatile machine perfusion (11 used the Waters perfusion machine), 6 pumped marginal cadaver kidneys, and the remaining 6 pumped all cadaver kidneys. Minimum perfusion criteria, pulse rates, perfusate composition, pressures, renal resistance, and renal pressure and flow were considered. Vasodilators and other machine additives were used to improve flow. The variance in each center's number of cadaver kidneys pumped each year, as well as the differences in pump times, was noted.

CONCLUSION

Twelve centers use pulsatile machine perfusion. A variety of techniques are used to perform pulsatile machine perfusion, but 11 of 12 have less delayed graft function than those programs employing ice storage preservation.

Studies on the release of solubilized drugs from ointment bases. Part 10: Modelling of the drug release process of chloramphenicol from emulsive ointments (W/O)--discussion

A mathematical model has been analyzed for the liberation process of substances (chloramphenicol) from emulsive ointments (W/O). Limitarying approximations have been derived which are useful for practical calculations. These approximations have been elaborated for the following cases: since the mass transfer resistance of diffusing substance occurs in the continuous phase, since the mass transfer resistance occurs only in the dispersed phase, then the mass transfer resistance in both phases is comparable. Experimental investigations have been carried out for the liberation process of substances from emulsive ointments. A good qualitative agreement has been found between the theoretical projections and experimental results.

Studies on the release of solubilized drugs from ointment bases. Part 9: Modelling of drug release process of active substance from emulsive ointments (W/O)--the mathematical model

A new mathematical model of the release process of solubilized active substance from emulsive (W/O) ointments is proposed. This model is based on Fick's diffusion law and additional assumptions. The most important assumption is recognition of the heterogeneous character of emulsive ointments. An equation has been derived, which expresses the functional relationship between the quantity of substance liberated from the ointment and the period of release.