Erythrocytes offer the exciting opportunity of being used as carriers of therapeutic agents. Encapsulation within erythrocytes will give the therapeutic agent a clearance equivalent to the normal life of the erythrocyte therefore maintaining therapeutic blood levels over prolonged periods and also giving a sustained delivery to the monocyte–macrophage system (reticulo-endothelial system). Both the dose and frequency of therapeutic interventions could thus be reduced. Ensuring a near-physiological survival time of carrier erythrocytes is essential to their successful use as a sustained drug delivery system, and this has not been demonstrated in man. In this study we assessed the survival in vivo of autologous unloaded energy-replete carrier erythrocytes in nine volunteers, using a standard 51Cr erythrocyte-labelling technique. Within 144 h after infusion there was a 3 to 49% fall in circulating labelled cells, followed thereafter by an almost complete return to initial circulating levels; surface counting demonstrated an initial sequestration of erythrocytes by the spleen and subsequent release. Mean cell life and cell half-life of the carrier erythrocytes were within the normal range of 89 to 131 days and 19 to 29 days respectively. These results demonstrate the viability of carrier erythrocytes as a sustained drug delivery system.
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February 1999
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Research Article|
February 01 1999
Survival of human carrier erythrocytes in vivo
Bridget E. BAX;
1Paediatric Metabolism Unit, Department of Child Health, St George's Hospital Medical School, London SW17 0RE, U.K.
Correspondence: Dr B. E. Bax.
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Murray D. BAIN;
Murray D. BAIN
1Paediatric Metabolism Unit, Department of Child Health, St George's Hospital Medical School, London SW17 0RE, U.K.
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Peter J. TALBOT;
Peter J. TALBOT
*Department of Haematology, St George's Hospital Medical School, London SW17 0RE, U.K.
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E. John PARKER-WILLIAMS;
E. John PARKER-WILLIAMS
*Department of Haematology, St George's Hospital Medical School, London SW17 0RE, U.K.
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Ronald A. CHALMERS
Ronald A. CHALMERS
1Paediatric Metabolism Unit, Department of Child Health, St George's Hospital Medical School, London SW17 0RE, U.K.
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Publisher: Portland Press Ltd
Received:
June 22 1998
Revision Received:
August 21 1998
Accepted:
August 25 1998
Online ISSN: 1470-8736
Print ISSN: 0143-5221
The Biochemical Society and the Medical Research Society © 1999
1999
Clin Sci (Lond) (1999) 96 (2): 171–178.
Article history
Received:
June 22 1998
Revision Received:
August 21 1998
Accepted:
August 25 1998
Citation
Bridget E. BAX, Murray D. BAIN, Peter J. TALBOT, E. John PARKER-WILLIAMS, Ronald A. CHALMERS; Survival of human carrier erythrocytes in vivo. Clin Sci (Lond) 1 February 1999; 96 (2): 171–178. doi: https://doi.org/10.1042/cs0960171
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