1 Division of Urology, Robert Wood Johnson Medical School, Camden, New Jersey, 2 Fertility Research Laboratories, North ShoreLong Island Jewish Institute for Medical Research, Manhasset, New York, 3 Department of Obstetrics and Gynecology, North Shore University Hospital, North ShoreLong Island Jewish Health System, Manhasset, New York and 4 Departments of Obstetrics & Gynecology and Cell Biology, New York University School of Medicine, New York, USA
5 To whom correspondence should be addressed at: North ShoreLong Island Institute for Medical Research, 350 Community Drive, Room 125, Manhasset, NY 11030, USA. Email: sbenoff{at}nshs.edu
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Abstract |
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Key words: biopsy/percutaneous aspiration/testis/ultrasound/varicocele
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Introduction |
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The varicocele alone may not be the primary cause of infertility. An understanding of spermatogenic defects in varicoceles seems a prerequisite for treatment, as Holstein et al., (2003) suggested. The interaction of varicoceles with other molecular and genetic factors may produce the infertile state (2nd Hit Hypothesis). In considering this, we have, among others, examined panels of molecular and genetic markers as predictors of varicocele surgery outcome (Benoff and Gilbert, 2001
; Marmar, 2001
; Benoff and Marmar, 2004
). For example, Steger et al., (2001)
related decreased protamine-1 and -2 mRNA content of round spermatids seen in testis biopsies to decreased fecundity of ejaculated sperm. Others have related a variety of semen markers to spermatogenesis (Behr and Weinbauer, 2000
; Francavilla et al., 2000
; Kimmins et al., 2004
).
We have chosen to work with testes tissue instead of semen because testis histology has been of use in varicocele assessment. The Johnsen (1970) score of testis biopsies correlates with ejaculate sperm density (Johnsen and Agger, 1978
; Abdelrahim et al., 1993
; Uygur et al., 1999
). However, the prognostic value of histological studies in isolation is equivocal. Premature sloughing of immature germ cells and maturation arrest is the predominant pathology reported, but these findings are not uniform (review: Benoff and Gilbert, 2001
). For example, McFadden and Mehan (1978)
reported that tubular basement membrane thickness was indicative of poor surgical outcome, while Abdelrahim et al., (1993)
found that varicocelectomy did not decrease tubular basement membrane width in matched pre-operative and post-operative bilateral testicular biopsies, a finding consistent with our own (Benoff et al., 2003
).
In connection with our studies, we were concerned about potential morbidity. This is a serious problem for open biopsies. Dardashti et al. (2000) reported a 3.4% complication rate for open testis biopsies (including scrotal haematomas requiring surgical drainage and testicular atrophy). Post-open-biopsy ultrasound studies revealed persistent hypoechoic testicular lesions for up to 6 months (Schlegel and Su, 1997
; Ron-El et al., 1998
). Percutaneous needle biopsies have fewer poor outcomes. Coviello et al., (2004)
reported using a narrow 19 gauge needle for repeated percutaneous biopsies in the same patient without tissue trauma. But where multiple percutaneous procedures per patient were performed, Harrington et al., (1996)
detected hypoechoic intratesticular lesions in 7% of patients at 6 months. In contrast, when one percutaneous stick was performed, Jarow et al., (2001)
found no intratesticular lesions by ultrasound 2 months post. These were relatively atraumatic because they utilized fine-needle aspirations to acquire cells, but they were blind procedures that did not preserve the tissue for histology. We therefore considered single stick procedures to study testis with modifications to ensure that the biopsy would be informative. Others have added real-time ultrasound to testes biopsies (Foresta et al., 1998
; Ron-El et al., 1998
; Belenky et al., 2001
; Raviv et al., 2004
) to increase safety by identifying areas of reduced and increased vascularity, similar to techniques that assessed ovarian vascularity during transvaginal puncture (Chui et al., 1997
; Van Blerkom et al., 1997
; Van Blerkom, 2000
). We therefore modified our percutaneous aspiration biopsy technique (Marmar, 1996
) to include ultrasonic guidance. We have reported the histology of testis biopsies so obtained at the time of varicocelectomy (e.g. Benoff et al., 2004
).
This report has two goals: (i) to document the safety of the single stick, ultrasonically guided percutaneous testis deep-aspiration biopsy technique; and (ii) to assess the efficacy of two examples of molecular markers in bilateral versus unilateral testis biopsies to predict the outcome of varicocele surgery [tissue cadmium concentration, and alterations in the L-type voltage-dependent calcium channel (L-VDCC) mRNA sequence]. Testicular cadmium concentration was chosen as an initial test marker as high tissue levels are associated with loss of actin and increased apoptosis that determines final sperm density (Benoff and Gilbert, 2001; Benoff et al., 2004
). It is likely that cadmium enters cells of the seminiferous epithelium via L-VDCC containing the
1C subunit (Benoff et al., 2005
). Alterations in the L-VDCC were chosen as an initial test marker as variant L-VDCC
1C mRNA with deletions in exons 7 and/or 8 (controlling, respectively, ion-selection properties and voltage-dependent channel inactivation) correlate with increased cadmium and apoptosis, and with poor response to varicocelectomy (Benoff et al., 2005
).
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Materials and methods |
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Human subjects
All protocols employing human subjects were reviewed and approved by the Institutional Review Boards of North Shore University Hospital and Cooper Hospital. Percutaneous testis aspiration biopsies were obtained (with written informed consent) with a single stick and ultrasonic guidance either from 115 infertile men at varicocele repair (by the subinguinal microsurgical approach; Marmar and Kim, 1994). The control group consisted of five men with proven fertility and obstructive azoospermia who required testicular sperm for IVF/ICSI because of a prior vasectomy. Although in animal models it has been shown that obstructive azoospermia is associated with important deterioration of spermatogenesis, including apoptosis (Lohiya et al., 1987
), the biopsies from control subjects all had normal histology, normal cadmium levels (0.194±0.104 ng/mg dry weight; see Benoff et al., 2004
) and expressed full-length L-VDCC amplicons (see Benoff et al., 2005
). Hence, these men were considered as suitable controls. No patient had a biopsy solely for research purposes and no patient had been previously studied. All specimens were anonymized prior to transfer to the laboratories at the North ShoreLIJ Research Institute.
Testis biopsies
Prior to the testis biopsies, complete medical histories, including occupational exposures and a drug/medication profile, were obtained for all males evaluated for primary infertility. Potentially confounding lifestyle variables were addressed during this initial consultation, including smoking habits, alcohol intake and the use of vitamins or dietary supplements.
Comprehensive multi-system physical examinations were performed. Testicular sizes of each patient were measured by a Prader orchidometer. The patients were examined in the upright position by palpation and with a pencil Doppler during a Valsalva manoeuvre. A varicocele was considered significant only when the reflux was continuous during the val-salva. The classification of size was consistent with Marmar and Kim (1994): grade 1, audible; grade 2, audible and palpable; and grade 3, audible, palpable and visible.
Subinguinal microsurgical varicocelectomies were performed on patients with Doppler positive lesions and at least one semen parameter below World Health Organization standards. These patients had bilateral biopsies at the time of surgery with ultrasonic guidance using the following protocol. The testis was grasped and immobilized with gauze at its base. A 510 MHz ultrasound probe was used to capture the gray scale image, colour Doppler and power Doppler images. The initial gray scale image demonstrated the homogeneous seminiferous tissue, whereas the latter studies localized major intratesticular vessels. Xylocaine (1%) was administered to the scrotal skin over an area away from major vessels. An 18 gauge, 1 inch angiocath and stylet were inserted at the anaesthetized site through the skin, tunic albuginea and seminiferous tissue away from major vessels. The stylet was removed. The tip from a section of intravenous extension tubing attached to a 20 ml syringe was inserted into the hub of the angiocath. Negative pressure was created by a pistol grip. The seminiferous tissue was drawn into the angiocath and tubing with repeated in-and-out movements of the hub of the angiocath. Approximately 100200 mg of tissue were obtained. The specimen was consistent with a thin segment of one to three seminiferous tubules that were drawn up into the 0.2 mm lumen of the angiocath.
Similar procedures were performed on men who required testis biopsies as a source of sperm in association with IVF/ICSI. However, these men received 8 ml of Xylocaine (1%) into the spermatic cord prior to the procedure as a local anaesthetic. The men were told to wear support underwear for 5 days post-biopsy, apply ice for 23 h daily for 2 days and use acetaminophen (paracetamol) for discomfort.
Repeat grey scale images documented hypoechoic areas within the testis as ultrasonic defects. Colour Doppler and power Doppler ultrasound images were obtained immediately after the biopsy and again at 12 months post-biopsy to determine the position and perfusion of the intratesticular vessels.
Study design
Following the suggestion of Steger (2002), all biopsy material was immediately divided in two. One part was fixed in Bouin's solution and was used for histology performed at Cooper Hospital. The remainder was placed in formalin and transported to the North ShoreLIJ Research Institute. Formalin-fixed tissues were used in all molecular investigations because formalin has no effect on atomic absorption analyses (Benoff et al., 2004
) and also inactivates RNases (Benoff et al., 2005
).
Analyses of testicular cadmium levels, L-VDCC 1C mRNA sequence and apoptosis were performed as part of a larger prospective study examining parameters potentially predictive of the outcome of varicocele repair (e.g. Benoff and Marmar, 2004
). Not all assays were performed on all patients because of small biopsy size.
Pre-operative and post-operative semen data were collected according to the protocol previously described (Marmar and Kim, 1994; Benoff et al., 2004
, 2005
). Pre-operatively, each patient provided at least three semen specimens within 6 months. Each specimen was collected by masturbation after 48 h of abstinence. The sperm density and percentage motility were determined with a Makler chamber. The morphology was reported according to the criteria established by the World Health Organization (1987)
. The semen results were averaged for each patient and a single value was computed for each parameter. The patient was considered for surgery so long as the duration of infertility was >12 months and the average value for any single semen parameter was less than a specified threshold (<20 x 106 sperm/ml, <50% motility and/or <30% normal morphology by modified strict criteria). Post-operatively, two or three additional semen samples were obtained over a 312 month period. The average value was computed for each parameter for statistical comparison to the pre-operative average value.
In previous studies (Marmar and Kim, 1994), we considered post-operative pregnancy data for statistical analysis, but these earlier studies had follow-up of
18 months. We needed a parameter with which to evaluate the male in his own right, as with infertile couples one can never be completely confident that all female factors have been eliminated. A panel of experts has reported that the likelihood of fecundity decreases with decreasing sperm concentration (Guzick et al., 2001
). We took our cue from this study. In the present report, patients were followed for <4 months and spermatogenic response to varicocele repair was used as a surrogate for collection of data on pregnancy outcomes in the varicocele population. A normal (=positive) response to varicocele surgery was defined as >50% increase in sperm density [(average post-operative sperm count minus average pre-operative sperm count)/average post-operative sperm count]. This value was chosen based on our previous study showing >50% increase in sperm density in patients who achieved pregnancy after varicocelectomy (Benoff et al., 2004
). This statistical technique has been used in other studies (e.g. Cayan et al., 2001
, 2002
).
Determination of cadmium levels in testis biopsies
Testicular cadmium concentrations were determined using established laboratory protocols. In brief, cadmium levels in individual testis biopsy fragments that had been lyophilized to a constant weight and microwave digested in 50% HNO3 were assessed by graphite furnace atomic absorption spectroscopy as previously described (Benoff et al., 2004).
Based on studies of men with non-obstructive azoospermia and normal spermatogenesis, testicular cadmium levels 0.453 ng/mg dry weight were considered normal whereas those >0.453 ng/mg dry weight were classified as abnormal or high (Benoff et al., 2004
).
Examination of L-type voltage-dependent calcium channel (L-VDCC) 1C splice variant expression
RNA was isolated from portions of formalin-fixed human testis biopsies (750 mg) using a Purescript RNA Isolation kit (Gentra Systems Inc., USA) as previously described (Benoff et al., 2005).
Oligonucleotide primers (synthesized on an Applied Biosystems Model 394 DNA Synthesizer, USA) were designed to cross exonintron boundaries and thereby detect spliced mature mRNA sequences in exons 69 in the L-VDCC 1C subunit (HUCH 2F and HUCH 1611R; Benoff et al., 2005
), and to amplify control mRNA (containing exons 8 and 9 of human glyceraldehyde-3-phosphate dehydrogenase (GAPDH; HG 690F and HG 984R; Goodwin et al., 2000
). RTPCR amplification followed our established laboratory protocols (Goodwin et al., 2000
; Benoff et al., 2005
). Lengths of PCR products from GAPDH primers were estimated by electrophoresis with 1 kb (Gibco-BRL, USA; cat. no. 5615SB) and 100 bp (Invitrogen, USA; cat. no. 15628-019) ladders on a 1.2% agarose gel (Shelton Scientific, USA). L-VDCC primer product sizes were estimated on 2% low melting point agarose gel (Biorad, USA; cat. no. 162-0019) using the same standards. Size-separated nucleic acids were visualized following ethidium bromide staining and photographed using a Gel Doc 1000 video camera (Bio-Rad Laboratories, USA). PCR products were gel-purified (Wizard PCR Preps; Promega, USA) and sequenced (DNA Sequencing System Model 373A; Applied Biosystems, USA) following manufacturer's protocols. Amplicons were compared with target sequences using the MacVector 5.0 Program (Kodak, USA).
Previous studies have demonstrated consistent expression of one full-length (532 bp) L-VDCC 1C amplicon and variable co-expression of four smaller splice variants (232520 bp) in testis biopsies from men with obstructive azoospermia (Benoff et al., 2005
). In contrast, the full-length (532 bp) L-VDCC
1C amplicon was detected in fewer than half of testis biopsies from infertile men with varicoceles. Its absence has been associated with poor varicocelectomy outcome (Benoff et al., 2005
).
Analysis of apoptosis
Apoptosis in testis biopsy sections was quantified by in situ by deoxynucleotidyl transferase labelling (TUNEL) of testis biopsy sections using TACS 2 TdT-DAB In Situ Apoptosis Detection Kit (cat. no. 4810-30-K; Trevigen, Inc., USA) as previously described (Benoff et al., 2004).
Statistical analyses
All statistical analyses were performed with the SigmaStat v.3.0 software package (SPSS, Inc., USA). Statistical significance was set at P<0.01.
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Results |
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Pre- and post-biopsy ultrasounds were performed on a subgroup (Figure 1; n=51) of the subjects with varicoceles (Figure 2, typical results). Post-biopsy ultrasounds were obtained immediately after the procedure and again at 2 months. Review of these patients charts revealed that the majority of patients (40/51 = 78.3%) exhibited no ultrasound defects immediately after the biopsy on the grey scale image (Table Ia). When hypoechoic defects were seen post biopsy, they averaged 23 mm and never exceeded 5 mm. By 2 months, 100% of the study group had no demonstrable ultrasonic defect on the grey scale study (Table Ib). Follow-up colour and power Doppler studies indicated that the intratesticular vasculature remained in the same position and the perfusion was unchanged in all patients (Figure 2, typical results).
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Mean pre-operative and post-operative semen parameters were available for 21 of these subjects. Seminal improvement post-surgery differed between the three groups described above [analysis of variance (ANOVA), P<0.001]. Applying post hoc pairwise comparisons by the HolmSidak method, group 1 exhibited an abnormal response (fraction increase in sperm density post-operatively = 0.274±0.212) that differed from groups 2 and 3 (P<0.0001). In contrast, groups 2 and 3 exhibited normal response (respectively, 0.655±0.235 and 0.891±0.050; not significant). Therefore, groups 2 and 3 were combined for the purposes of bilateral L-VDCC 1C amplicon analyses (Table IVd).
Although unilateral or bilateral absence of full-length L-VDCC 1C amplicons predicted low abnormal response to varicocele surgery, the bilateral analyses resolved two of the four cases with discordance on unilateral measurements (Tables IVc and IVd). As observed for cadmium, bilateral L-VDCC
1C analyses was more powerful than unilateral, with an overall accuracy of 90.5% (Table V). These results suggested that bilateral examination of L-VDCC
1C splice variant expression might aid in the evaluation of infertile men with varicoceles.
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Discussion |
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Our data indicate that testis tissue can be acquired without testicular damage by single stick, ultrasonically guided percutaneous aspiration biopsies. When the angiocath puncture is made away from major intratesticular vessels, there was no evidence of intratesticular defect by grey scale at 2 months, and no vascular changes by colour/power Doppler. This is in agreement with observations of investigators who performed percutaneous biopsies under ultrasound (Belenky et al., 2001). The soft angiocath may help to minimize testicular defects because the biopsy is limited to a few stringy seminiferous tubules with a diameter of the angiocath's lumen. This biopsy technique has been used in >700 cases, including diagnostic biopsies of azoospermic men and sperm acquisition biopsies for IVF/ICSI. By this percutaneous procedure, the patients experienced less pain and swelling than with open biopsies. Although skin ecchymoses occasionally occurred, none required drainage and none of the patients had haematomas or permanent nodules. These findings contrast with open biopsies that may have a 3.4% complication rate (Dardashti et al., 2000
).
This biopsy technique preserved histology for study of varicoceles. Presently, some histological findings are being correlated with specific medical therapies in ongoing studies, including: (i) supplemental zinc (Takihara et al., 1987; Ando et al., 1989
, 1990
; Benoff, 1997
; Benoff et al., 1997
, 2000
), (ii) antioxidants (Barbieri et al., 1999
; Tripodi et al., 2003
; Onur et al., 2004
), and (iii) hormonal stimulation with Clomid (Bandhauer and Meili, 1977
; Check, 1980
; Unal et al., 2001
), tamoxifen (Kadioglu et al., 1999
) or hCG (Dubin and Amelar, 1977
; Yamamoto et al., 1995
; Yan et al., 2004
). We here demonstrate the usefulness of molecular data from these biopsies both in investigation of the mechanism of bilateral effects of left varicoceles, and in treatment planning.
Spermatogenesis is decreased bilaterally in testis biopsies both in cases with unilateral and with bilateral varicoceles (Etriby et al., 1975), and increased following varicocele repair (Charny, 1962
; Agger and Johnsen, 1978
; Johnsen and Agger, 1978
; Abdelrahim et al., 1993
). These authors proposed a hypothetical anastomosis between the left and right spermatic vein plexuses to explain the bilateral effects of left varicoceles. This was unsatisfying as this anatomical structure has never been adequately documented and led our group to propose the 2nd Hit Hypothesis (Benoff and Gilbert, 2001
; Marmar, 2001
).
Implicit in our 2nd Hit Hypothesis is the argument that factors intrinsic to varicoceles will be expressed at a higher level in subjects with bilateral varicoceles than those with left varicoceles, and that factors that are extrinsic will be expressed equally in both subject groups. Both testicular cadmium levels and L-VDCC microdeletions are extrinsic factors (Benoff et al., 2004, 2005
). This is supported by this report. Cadmium levels are discordant in about one-third of matched biopsies examined, and L-VDCC amplicon expression is discordant in about one-fourth of cases. Consequently, markers from a biopsy of one testis may be insufficient because both testes contribute to semen production. Therefore, we performed biopsies on both testes, even in cases with unilateral varicoceles. Although testicular damage as assessed by histology is often less severe in the contralateral testis (Etriby et al., 1967
; Ibrahim et al., 1977
; Hadziselimovic, 1995
), the molecular studies in matched left and right testis biopsies from individual patients with unilateral varicoceles showed unexpected concordances (Benoff et al., 2004
, 2005
). Therefore, bilateral biopsies seemed worth exploring by this low-morbidity procedure. For example, we found that apoptosis was elevated bilaterally in infertile men with varicoceles irrespective of whether the patient presented with a left varicocele or with bilateral lesions (Benoff et al., 2004
).
The measure of success for varicocelectomy used in this report was >50% increase in sperm density compared to pre-operative values, because this was the mean increase demonstrated by the patients that achieved pregnancy after surgery (Benoff et al., 2004). In addition, the patients were stratified by the expression of specific markers in the testis tissue (cadmium levels and L-VDCC
1C splice variants). However, we recognize that use of positive changes in sperm density as a surrogate for reproductive success has been challenged (Vigil et al., 1994
). Nevertheless, recent reports on the predictive value of the sperm density have supported its use. For example, Guzick et al. (2001)
compared sperm densities of fertile and subfertile populations. They demonstrated that the chances of subfertility increased as the sperm density decreased. Those within the range of 13.548x106 sperm/ml had an odds ratio of being in the subfertile population of 1.5 (1.22.2), whereas those with <13.5x106 sperm/ml had an odds ratio of 5.3 (3.38.3). In a separate report comparing fertile and subfertile populations, Ombelet et al., (1997)
reported that the mean sperm densities for these groups were 19.5 versus 8.5 x 106/ml respectively (P<0.001). These data suggest that measurements of sperm densities may help to define the fertility status.
Since pregnancy rates after varicocele surgery are only 3540%, these molecular markers should help to pre-select patients who would benefit most. In this report, when we stratified patients by normal and abnormal tissue cadmium and microdeletions in L-VDCC, those with normal markers had likelihood ratios of >50% improvement of sperm density of 4.95 and 6.49 respectively. In contrast, those with abnormal markers had only a ratio of 0.28 and 0.08 for improvement. We intend to survey and update the pregnancy data among these patients (couples). With these data, we hope to add additional outcome information to validate this diagnostic approach.
Since this study shows that percutaneous testis biopsies with ultrasonic control are safe, urologists may consider using these biopsies and these markers as part of their pre-operative work-up. Although cadmium measurements can be performed by most hospital laboratories, analysis of L-VDCC 1C splice variant expression may require a more sophisticated setting. Nevertheless, we hope that reference laboratories will make this test available in the future.
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Acknowledgements |
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References |
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Submitted on November 24, 2004; resubmitted on February 10, 2005; accepted on March 17, 2005.
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