Rejection severity directly correlates with myocyte apoptosis in pig-to-baboon cardiac xenotransplantation

Joel G R Weaver, Christopher G A McGregor, Henry D. Tazelaar, Andrew David Badley

Research output: Contribution to journalArticle

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Abstract

Background: The process by which cardiac myocytes die during xenograft rejection is incompletely understood. The presence of cardiac myocyte apoptosis in discordant xenotransplant models has been noted, yet no investigators have examined whether a relationship between myocyte apoptosis and rejection severity exists. Thus, we chose to further investigate this observation. Methods: Eight explanted pig-to-baboon cardiac grafts with varying severities of rejection, as determined by hematoxylin and eosin histology, were examined for apoptosis by transmission electron microscopy (TEM) and TUNEL (terminal deoxynucleotide transferase-mediated digoxigenin-dUTP nick-end labeling) immunohistochemistry. In addition, Western blot analysis for the cleavage of the apoptosis regulatory proteins pro-caspase 8 and 3 was performed. Results: Transmission electron microscopy revealed that a severely rejected graft displayed widespread condensation of nuclear chromatin, which is a characteristic morphologic feature of apoptosis. TUNEL staining verified this observation and allowed for the quantification of myocyte apoptosis in each graft. Subsequent linear regression analysis of the extent of myocyte apoptosis and rejection severity revealed a direct correlation (R2 = 0.757, p = 0.005). In addition, Western blot analysis demonstrated that myocyte apoptosis involves the cleavage of pro-caspase 8 and 3. Conclusions: Myocyte death in rejecting pig-to-baboon cardiac xenografts occurs through an apoptotic pathway and directly correlates with the severity of graft rejection. Further studies aimed at elucidating the apoptotic stimulus are therefore warranted. Moreover, our data suggest that antiapoptotic strategies may be of benefit in the treatment of xenograft rejection.

Original languageEnglish (US)
Pages (from-to)841-847
Number of pages7
JournalJournal of Heart and Lung Transplantation
Volume24
Issue number7
DOIs
StatePublished - Jul 2005

Fingerprint

Heterologous Transplantation
Papio
Muscle Cells
Swine
Apoptosis
Heterografts
Caspase 8
In Situ Nick-End Labeling
Transmission Electron Microscopy
Transplants
Cardiac Myocytes
Caspase 3
Western Blotting
Digoxigenin
Apoptosis Regulatory Proteins
Graft Rejection
Hematoxylin
Eosine Yellowish-(YS)
Transferases
Chromatin

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Surgery
  • Transplantation

Cite this

Rejection severity directly correlates with myocyte apoptosis in pig-to-baboon cardiac xenotransplantation. / Weaver, Joel G R; McGregor, Christopher G A; Tazelaar, Henry D.; Badley, Andrew David.

In: Journal of Heart and Lung Transplantation, Vol. 24, No. 7, 07.2005, p. 841-847.

Research output: Contribution to journalArticle

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abstract = "Background: The process by which cardiac myocytes die during xenograft rejection is incompletely understood. The presence of cardiac myocyte apoptosis in discordant xenotransplant models has been noted, yet no investigators have examined whether a relationship between myocyte apoptosis and rejection severity exists. Thus, we chose to further investigate this observation. Methods: Eight explanted pig-to-baboon cardiac grafts with varying severities of rejection, as determined by hematoxylin and eosin histology, were examined for apoptosis by transmission electron microscopy (TEM) and TUNEL (terminal deoxynucleotide transferase-mediated digoxigenin-dUTP nick-end labeling) immunohistochemistry. In addition, Western blot analysis for the cleavage of the apoptosis regulatory proteins pro-caspase 8 and 3 was performed. Results: Transmission electron microscopy revealed that a severely rejected graft displayed widespread condensation of nuclear chromatin, which is a characteristic morphologic feature of apoptosis. TUNEL staining verified this observation and allowed for the quantification of myocyte apoptosis in each graft. Subsequent linear regression analysis of the extent of myocyte apoptosis and rejection severity revealed a direct correlation (R2 = 0.757, p = 0.005). In addition, Western blot analysis demonstrated that myocyte apoptosis involves the cleavage of pro-caspase 8 and 3. Conclusions: Myocyte death in rejecting pig-to-baboon cardiac xenografts occurs through an apoptotic pathway and directly correlates with the severity of graft rejection. Further studies aimed at elucidating the apoptotic stimulus are therefore warranted. Moreover, our data suggest that antiapoptotic strategies may be of benefit in the treatment of xenograft rejection.",
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