Prostatic peripheral nerve distribution may impact the functional outcome of nerve-sparing prostatectomy

Molecular characterization of human peripheral nerves using desorption electrospray ionization mass spectrometry imaging

Desorption electrospray ionization mass spectrometry imaging (DESI-MSI) is a molecular imaging method that can be used to elucidate the small-molecule composition of tissues and map their spatial information using two-dimensional ion images. This technique has been used to investigate the molecular profiles of variety of tissues, including within the central nervous system, specifically the brain and spinal cord. To our knowledge, this technique has yet to be applied to tissues of the peripheral nervous system (PNS). Data generated from such analyses are expected to advance the characterization of these structures. The study aimed to: (i) establish whether DESI-MSI can discriminate the molecular characteristics of peripheral nerves and distinguish them from surrounding tissues and (ii) assess whether different peripheral nerve subtypes are characterized by unique molecular profiles. Four different nerves for which are known to carry various nerve fiber types were harvested from a fresh cadaveric donor: mixed, motor and sensory (sciatic and femoral); cutaneous, sensory (sural); and autonomic (vagus). Tissue samples were harvested to include the nerve bundles in addition to surrounding connective tissue. Samples were flash-frozen, embedded in optimal cutting temperature compound in cross-section, and sectioned at 14 μm. Following DESI-MSI analysis, identical tissue sections were stained with hematoxylin and eosin. In this proof-of-concept study, a combination of multivariate and univariate statistical methods was used to evaluate molecular differences between the nerve and adjacent tissue and between nerve subtypes. The acquired mass spectral profiles of the peripheral nerve samples presented trends in ion abundances that seemed to be characteristic of nerve tissue and spatially corresponded to the associated histology of the tissue sections. Principal component analysis (PCA) supported the separation of the samples into distinct nerve and adjacent tissue classes. This classification was further supported by the K-means clustering analysis, which showed separation of the nerve and background ions. Differences in ion expression were confirmed using ANOVA which identified statistically significant differences in ion expression between the nerve subtypes. The PCA plot suggested some separation of the nerve subtypes into four classes which corresponded with the nerve types. This was supported by the K-means clustering. Some overlap in classes was noted in these two clustering analyses. This study provides emerging evidence that DESI-MSI is an effective tool for metabolomic profiling of peripheral nerves. Our results suggest that peripheral nerves have molecular profiles that are distinct from the surrounding connective tissues and that DESI-MSI may be able to discriminate between nerve subtypes. DESI-MSI of peripheral nerves may be a valuable technique that could be used to improve our understanding of peripheral nerve anatomy and physiology. The ability to utilize ambient mass spectrometry techniques in real time could also provide an unprecedented advantage for surgical decision making, including in nerve-sparing procedures in the future.

[Organoids for the advancement of intraoperative diagnostic procedures]

In the context of cancer surgery, there is always a trade-off between oncological safety and preservation of function. This is especially true in pelvic surgery due to the close relationship to the pelvic floor muscles, blood supply and nerves. Currently, risk models, preoperative imaging, the surgeon's assessment, and the intraoperative frozen section serve as the basis for decision-making. New imaging techniques and standardization in frozen section have significantly improved this in recent years. However, limitations remain due to time delays as well as more difficult correct anatomical assignment in the follow-up. Alternative intraoperative techniques may overcome this limitation in the future. Patient-derived organoids have emerged as an important new research vehicle in recent years. They are based on tumor stem cells that, under special culture conditions, form three-dimensional replicas of the original tissue. This makes them ideally suited for testing individual system therapies but also as a validation technique for new intraoperative diagnostic procedures. The Research Training Group 2543/I, which is funded by the German Research Foundation, is researching the potential of new diagnostic methods in an interdisciplinary team regarding validation in addition to intraoperative frozen sections.

[SALVAGE CRYOABLATION TARGETING RECURRENT LESIONS AFTER DEFINITIVE RADIOTHERAPY FOR PROSTATE CANCER: IMPACT OF POST CRYOABLATION CHANGE IN URINARY AND SEXUAL FUNCTION]

(Purpose) To describe our initial experience in salvage cryoablation targeting recurrent lesions after definitive irradiation for prostate cancer. (Methods) Eligible patients for this treatment were those who developed biochemical failure after definitive radiotherapy for localized prostate cancer, but without distant metastasis, and with solid lesions identifiable on multiparametric magnetic resonance imaging (mpMRI). Histological proof of recurrence with mapping biopsy covering corresponding sites was obtained. Two to four cryoprobes were inserted transperineally into the prostate under general anesthesia with extensive lithotomy position. The rapid expansion of argon gas cryogen through a small opening within the cryoprobe cools itself to make an ice ball and the quick exchange to helium gas induces an active thawing phase. Entire procedure is monitored and guided with the use of transrectal ultrasonography. Postoperative follow-up included patient interview, digital rectal examination, prostate specific antigen (PSA) testing and quality of life (QOL) monitoring using IPSS and IIEF-5 at 1, 3, 6 and 12 months postoperatively. Changes of mpMRI findings with time, particularly at one month, were used to judge immediate treatment impact. (Results) Five patients underwent salvage cryoablation between October 2015 and September 2016. No grade 3/4 complications such as rectal fistula or urethral stenosis were experienced. Mean and maximal percent decline of PSA from baseline levels at 1, 3, 6 and 12 months following cryoablation were 72.2 and 94.7%, 79.4% and 93.9%, 78.2% and 92.1%, 79.6% and 90.9%, respectively. Posttreatment IPSS showed temporary worsening with average changes in score of 1.8, 1.5, 1.6, and 1.0 times over baseline levels, respectively. IPSS score returned to the baseline in one at six months and two at 12 months. Two of 5 patients were sexually active prior to therapy and thus evaluable. Both showed significant decline in IIEF score by 95% at 12 months. No patients showed any signs of recurrence. mpMRI at one month following cryoablation confirmed complete disappearance of visible lesions in all cases. (Conclusions) Salvage cryoablation for recurrent lesions of prostate cancer after definitive radiotherapy is feasible with minimal morbidity. Both oncological outcome and adverse events should be monitored carefully with longer follow up.