Comparison of enzymatic digestion and mechanical dissociation of human testicular tissues

Capsule:
Medimachine dissociation of human testicular tissues results in a cell suspension enriched for SALL4-positive undifferentiated spermatogonia.

Authors:
Florian Schneider, M.D., Klaus Redmann, Ph.D., Joachim Wistuba, Ph.D., Stefan Schlatt, Ph.D., Sabine Kliesch, M.D., Nina Neuhaus, Ph.D.

Volume 104, Issue 2, Pages 302-311

Abstract:

Objective:
To compare mechanical dissociation, employing the Medimachine system, and enzymatic digestion of human testicular tissues with respect to the proportion of spermatogonia and somatic cells, with the long-term objective of establishing human spermatogonial cultures.

Design:
Experimental basic science study.

Setting:
Reproductive biology laboratory.

Patient(s):
Testicular tissues were obtained from patients with gender dysphoria on the day of sex reassignment surgery. On the basis of the histological evaluation, tissue samples with complete spermatogenesis (fresh, n = 6; cryopreserved, n = 7) and with meiotic arrest (cryopreserved, n = 4) were selected.

Intervention(s):
None.

Main Outcome Measure(s):
The composition of testicular cell suspensions was assessed performing quantitative real-time polymerase chain reaction (qPCR) analyses for germ cell–specific (FGFR3, SALL4, UTF1, MAGE-A4) and somatic marker genes (ACTA2 and VIM). Additionally, flow-cytometric analyses were used to evaluate the percentage of SALL4-and vimentin-positive cells.

Result(s):
While Medimachine dissociation yielded higher cell numbers in all patient groups, viability of cells was highly variable and correlated with the histological status of the tissue. Interestingly, qPCR analysis revealed a significantly decreased expression of the somatic marker genes ACTA2 and VIM and an increased expression of the spermatogonial marker genes FGFR3 and SALL4 after Medimachine dissociation. These findings were corroborated by flow-cytometric analyses that demonstrated that the proportion of SALL4-positive cells was up to 4 times higher after mechanical dissociation.

Conclusion(s):
Medimachine dissociation of human testicular tissues is comparably fast and leads to an enrichment of SALL4-positive spermatogonia. The use of this method may therefore constitute an advantage for the establishment of human spermatogonial cell cultures.

  • The authors attempt to identify a method to enrich cultures from testicular tissue with spermatogonial rather than somatic cells. Is the Medimachine better than mechanical digestion with scissors and passing through a 24g angiocath? Can the authors hypothesize as to why chemical digestion did not enrich SALL4 (+) cells?

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