Synthesis and characterization of a novel DTPA polymerized hemoglobin based oxygen carrier

Chad R. Haney*, Paul W. Buehler, Anil Gulati

*Corresponding author for this work

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Objective: The purpose of this study was to prepare a novel polymerized hemoglobin (Hb) based oxygen carrier (HBOC) designed to minimize Hb induced hypertension, while employing a simple and inexpensive method of preparation. Cyclic-diethylenetriaminepentaacetic acid (DTPA) was used to polymerize stroma free Hb (SF-Hb). Methods: SF-Hb was isolated from red blood cells and reacted with DTPA at a constant concentration, pH, and duration. Low molar mass fractions (<100 kDa) were removed using ultrafiltration. Reactions and subsequent ultrafiltration steps were determined to be reproducible by analyzing molar mass, colloid osmotic pressure and oxygen affinity. Finally, a model of 50% exchange transfusion (ET) in rats was used to evaluate the blood pressure response to DTPA polymerized SF-Hb (Poly-DTPA-Hb). Results: Poly-DTPA-Hb demonstrated a number averaged molar mass of 128.7 kDa and a weighted average of 223.0 kDa. Oxygen binding equilibrium indicated high oxygen affinity (P 50 = 5.1 ± 0.01 mm Hg) and little cooperativity (n = 1.4). Poly-DTPA-Hb and a control DTPA polymerized human serum albumin (Poly-DTPA-HSA) unexpectedly caused acute hypotension during the period of ET in rats (mean arterial pressure ≈45% less than baseline). Hypotension occurring over the period of ET was determined to be mediated by calcium binding to protein associated DTPA. This effect was attenuated by the addition of calcium chloride (CaCl2) to the Poly-DTPA protein preparations. Conclusions: Cyclic DTPA anhydride can be used to create cross-linked and polymerized hemoglobin, using a simple and inexpensive process. However, the addition of CaCl 2 to the preparation appears to be required to prevent calcium chelation and subsequent hypotension during infusion.

Original languageEnglish (US)
Pages (from-to)358-369
Number of pages12
JournalBiochimica et Biophysica Acta - General Subjects
Volume1725
Issue number3
DOIs
StatePublished - Oct 10 2005

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Keywords

  • Blood substitute
  • DTPA
  • Hemoglobin
  • Polymerization

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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