Author(s):
Sousa, Ana Paula 
; Amaral, Alexandra ; Baptista, Marta ; Tavares, Renata ; Caballero Campo, Pedro ; Caballero Peregrín, Pedro ; Freitas, Albertina ; Paiva, Artur ; Almeida-Santos, Teresa ; Ramalho-Santos, João
Date: 2011
Persistent ID: http://hdl.handle.net/10316/15679
Origin: Estudo Geral - Universidade de Coimbra
Description
Human sperm samples are very heterogeneous and include a low amount of truly functional gametes. Distinct strategies
have been developed to characterize and isolate this specific subpopulation. In this study we have used fluorescence
microscopy and fluorescence-activated cell sorting to determine if mitochondrial function, as assessed using mitochondrialsensitive
probes, could be employed as a criterion to obtain more functional sperm from a given ejaculate. We first
determined that mitochondrial activity correlated with the quality of distinct human samples, from healthy donors to
patients with decreased semen quality. Furthermore, using fluorescence-activated cell sorting to separate sperm with active
and inactive mitochondria we found that this was also true within samples. Indeed, sperm with active mitochondria defined
a more functional subpopulation, which contained more capacitated and acrosome intact cells, sperm with lower chromatin
damage, and, crucially, sperm more able to decondense and participate in early development using both chemical
induction and injection into mature bovine oocytes. Furthermore, cell sorting using mitochondrial activity produced a more
functional sperm subpopulation than classic swim-up, both in terms of improvement in a variety of functional sperm
parameters and in statistical significance. In conclusion, whatever the true biological role of sperm mitochondria in
fertilization, mitochondrial activity is a clear hallmark of human sperm functionality. Fundação para a Ciência e Tecnologia (POCTI/CVT/49102/2002; SFRH/BD/23571/2005; SFRH/BPD/63120/2009; SFRH/BD/46002/2008; SFRH/BD/46078/2008) Instituto de Investigação Interdisciplinar da Universidade de Coimbra (III/BIO/50/2005)
