Detection of rare Leydig cell hypoplasia in somatic cell cloned male piglets

Abstract

In this investigation, 22 cloned male piglets were obtained by male fetal fibroblast-cell-derived nuclear transfer. Eighteen of the cloned animals died. The two cell lines did not differ significantly with regard to efficiency of live piglet production. The gross anatomy of the testes of male piglets that died was normal. However, one piglet displayed Leydig cell hypoplasia (LCH). No anatomical defects were detected in the testes of other cloned male piglets. TUNEL analysis of the testis with LCH revealed significant apoptosis in the Leydig cells, while apoptosis was rarely detected in Sertoli cells and spermatogonia. In contrast, testes from the remaining 17 piglets that died appeared normal in size, and their Sertoli and Leydig cell numbers were comparable to those in control piglet testes. Although cloned piglets were derived from fibroblasts obtained from the same fetus, phenotypic instability between cells used for the production of somatic cell cloned piglets suggests that abnormalities in male cloned piglets are caused not by technical problems and/or reprogramming effects, but rather by epigenetically and/or genetically damaged cell-specific effects.

Serial cloning of pigs by somatic cell nuclear transfer: Restoration of phenotypic normality during serial cloning

“…The scNT clones showed a higher incidence of postnatal death compared with the AI-derived piglets (5/144, 4.4%; three were stillborn and two were crushed). Histological analyses of 28 of the 38 scNT clones that died after birth revealed 11 had distinct histological anomalies, the most common of which was meningitis, followed by poor development of the elbow joint bone, flexor tendons, congestion, and Leydig cell hypoplasia (Park et al, 2004(Park et al, , 2005. As shown in our very recent report, the abnormal histopathologic findings of the deceased cloned pigs are closely associated with aberrant protein expression patterns (Park et al, 2005;Chae et al, 2006;Lee et al, 2007).…”

“…We and authors of another study reported that phenotypic instability in swine resulted from scNT Archer et al, 2003;Park et al, 2004Park et al, , 2005. However, other groups have observed few problems (Betthauser et al, 2000;De Sousa et al, 2002;Walker et al, 2002;Yin et al, 2002).…”

“…NT was carried out as described previously (Yin et al, 2003;Park et al, 2004, Chae et al, 2006Lee et al, 2007). Briefly, the matured eggs with the first polar body were cultured in NCSU-23 medium supplemented with 0.4 mg/ml demecolcine (Sigma) and 0.05 mol/L sucrose for 1 hr.…”

“…An important advancement was made in the field recently when several research groups succeeded in cloning piglets from somatic cells (Betthauser et al, 2000;Onishi et al, 2000;Polejaeva et al, 2000;Bondioli et al, 2001;Yin et al, 2002Yin et al, , 2003Park et al, 2004Park et al, , 2005. This finding has permitted the genetic improvement of farmed pigs and the production of transgenic pigs for medical use and organ transplantation .…”

“…It should be noted, however, that some of the phenotypic effects of scNT cloning, such as increased size and mass, polydactyly, swollen edematous skin, and perinatal death, have also been observed in embryonic stem cell-derived animals (Dean et al, 1998). However, compared with other reproductive assistant techniques, scNT cloning is associated with particularly high levels of phenotypic instability (Hill et al, 1999;Cibelli et al, 2002;Hiendleder et al, 2004;Park et al, 2004Park et al, , 2005, as 64% of cattle, 40% of sheep, 60% of pigs, and 93% of mice exhibit some form of abnormality, such as pulmonary hypertension and respiratory distress. For example, goat and pig clones are prone to bacterial infections of the lungs, abnormal numbers of teats, cleft lips, malformed limbs, an atrial septal defect, a cranial abnormality, and contracted tendons Piedrahita et al, 2004;Lee et al, 2005).…”