DEPROMP Trial: the additive value of PSMA-PET/CT-guided biopsy for prostate cancer management in biopsy naïve men-study protocol for a randomized trial

BACKGROUND

The primary objective is to determine the proportion of men with suspected prostate cancer (PCA) in whom the management plans are changed by additive gallium-68 prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA-PET/CT) guided prostate biopsy (PET-TB) in combination with standard of care (SOC) using systematic (SB) and multiparametric magnetic resonance imaging-guided biopsy (MR-TB) compared with SOC alone. The major secondary objectives are to determine the additive value of the combined approach of SB + MR-TB + PET-TB (PET/MR-TB) for detecting clinically significant PCA (csPCA) compared to SOC; to determine sensitivity, specificity, positive and negative predictive value and diagnostic accuracy of imaging techniques, respective imaging classification systems, and each biopsy method; and to compare preoperatively defined tumor burden and biomarker expression and pathological tumor extent in prostate specimens.

METHODS

The DEPROMP study is a prospective, open-label, interventional investigator-initiated trial. Risk stratification and management plans after PET/MR-TB are conducted randomized and blinded by different evaluation teams of experienced urologists based on histopathological analysis and imaging information: one including all results of the PET/MR-TB and one excluding the additional information gained by PSMA-PET/CT guided biopsy. The power calculation was centered on pilot data, and we will recruit up to 230 biopsy-naïve men who will undergo PET/MR-TB for suspected PCA. Conduct and reporting of MRI and PSMA-PET/CT will be performed in a blinded fashion.

DISCUSSION

The DEPROMP Trial will be the first to evaluate the clinically relevant effects of the use of PSMA-PET/CT in patients with suspected PCA compared to current SOC. The study will provide prospective data to determine the diagnostic yields of additional PET-TB in men with suspected PCA and the impact on treatment plans in terms of intra- and intermodal changes. The results will allow a comparative analysis of risk stratification by each biopsy method, including a performance analysis of the corresponding rating systems. This will reveal potential intermethod and pre- and postoperative discordances of tumor stage and grading, providing the opportunity to critically assess the need for multiple biopsies.

TRIAL REGISTRATION

German Clinical Study Register DRKS 00024134. Registered on 26 January 2021.

Factors influencing the implementation of school interventions: a systematic review

Background

To investigate contextual factors that influence the implementation of obesity prevention interventions in school addressing children with low socioeconomic status (SES) is very important. Evidence about these factors helps to improve the implementation, which can promote the health of children with low SES and therefore reduce health inequity. We aimed to systematically identify, critically appraise and summarize the evidence on implementation of school-based interventions promoting obesity prevention for children with low SES.

Methods

A systematic search in seven databases was conducted with the main inclusion criteria 1) school-based interventions and 2) age group 5-14 years. The Consolidated Framework for Implementation Research and its five domains and 39 categories was used to analyze the data deductively. If necessary, inductive sub-categories were defined within the categories. Contextual factors are assessed in the domain Outer Setting with four categories (A-D).

Results

6.446 studies were screened and 16 studies fulfilled all inclusion criteria. Seven studies reported contextual factors in the four categories A. Needs & resources of parents (N = 4), B. Cosmopolitanism (N = 4), C. Peer pressure (N = 2), and D. External policy (N = 4) with seven sub-categories in total. In the following are examples for reported aspects in the sub-categories. In the sub-category D.2 Existing policy, policy in line with the intervention was a facilitator for implementation (N = 2), whereas lack of control over administrative changes and food served in cafeteria due to policy were reported as barriers (N = 2).

Conclusions

Intervention research as well as applied health promotion should consider the complexity and interdependency of influencing factors for successful implementation. Albeit contextual factors are hardly changeable, they should be considered and addressed to reduce health inequity.

Key messages

• More research is needed with detailed reporting of influencing factors, as detailed information is those of relevance for practice.

• Contributing to standardized analysis and reporting in implementation research by using a comprehensive framework.

The lncRNA Fer1L4 is an adverse prognostic parameter in clear-cell renal-cell carcinoma

Purpose

Long non-coding RNAs (lncRNA) are involved in oncogenesis and tumor progression in various tumor entities. At present, little is known about the role in tumor biology of the lncRNA Fer-1 like family member 4 (Fer1L4) in clear-cell renal-cell carcinoma (ccRCC). The aim of this study is to evaluate the expression of Fer1L4 in patients with ccRCC, its association with clinicopathological parameters, and value as prognostic biomarker.

Material and methods

The expression of Fer1L4 was analyzed in the TCGA ccRCC cohort (n = 603; ccRCC n = 522, normal n = 81) and subsequently validated by quantitative real-time PCR in an independent cohort (n = 103, ccRCC n = 69, normal n = 34). Expression profiles were statistically correlated with clinicopathological and survival data.

Results

Fer1L4 lncRNA is overexpressed in ccRCC compared to adjacent normal tissues. Increased expression significantly correlates with tumor aggressiveness: high expression levels of Fer1L4 RNA were found in higher grade, higher stage, and metastatic tumors. Furthermore, Fer1L4 overexpression is an independent prognostic factor for overall, cancer-specific, and progression-free survival of patients with ccRCC.

Conclusion

Fer1L4 expression significantly correlates with aspects of tumor aggressiveness. Based on this impact on tumor progression and its influence as an independent prognostic factor, Fer1L4 appears to exert properties as an oncogene in ccRCC. As a prognostic tissue biomarker, further functional investigations are warranted to investigate Fer1L4 as a potential therapeutic target.

[When is surgical resection of the primary tumor indicated in metastatic urothelial carcinoma of the bladder and what is the scientific rationale?]

Cisplatin-based polychemotherapy is still the standard therapy for metastatic urothelial carcinoma, although disease progression is often noted at an early time point even in patients with response. In recent years, cytoreductive surgery has been gaining increasing interest in many tumor entities in the setting of metastatic disease to improve patients outcome, but urothelial carcinoma is not regarded as a candidate for such a multimodal therapy approach. However, several retrospective studies suggest a survival benefit of radical cystectomy and/or metastasectomy for well-selected patients with metastatic urothelial carcinoma. Prognostically relevant parameters for consolidative cystectomy/metastasectomy after chemotherapy seem to be a distinct response to inductive chemotherapy and limited metastatic spread (regional lymph node, single lung metastasis).

[Detection of cell-free lncRNA in serum of cancer patients]

BACKGROUND

The analysis of circulating RNA molecules is of increasing interest since tumor-specific RNA expression patterns could be a useful cancer biomarker. A new entity of RNA molecules, the so-called long non-coding RNAs (lncRNA), are of particular interest because of its high tissue- and tumor-specificity. The importance of analytical factors in the quantification of lncRNAs is largely unclear and should therefore be investigated in the present study.

PATIENTS AND METHODS

Serum RNA was isolated from patients with bladder, prostate and kidney cancer as well as patients with non-malignant disease. Analytical variables like different RNA isolation procedures, cDNA synthesis and preamplification were studied with respect to quantification of MALAT1 and ACTB via real-time PCR.

RESULTS

The quantification of cell-free serum RNA is feasible although the levels of ACTB and MALAT1 were often only slightly above the detection limit. RNA isolation with a combined phenol-based column purification (Ambion mirVana PARIS miRNA Isolation Kit; Qiagen miRNeasy Serum/Plasma Kit) was most effective. The elimination of DNA contamination was most successful during cDNA synthesis with (Takara-Bio PrimeScript RT Reagent Kit with gDNA Eraser). Preamplification with the Applied Biosystems TaqMan PreAmp Master Mix Kit improved sensitivity. Serum ACTB and MALAT1 levels were not significantly increased in patients with urological tumors compared to patients with non-malignant diseases.

CONCLUSION

An optimized protocol for the analysis of circulating lncRNAs is described in the present study.

[Patients with bladder cancer in clinical stage T2 : survival benefit of downstaging in comparison to patients with confirmed muscle invasion in cystectomy specimens]

BACKGROUND

Few and partially contradictory data are available regarding the prognostic signature of downstaging of muscle-invasive clinical tumour stages in patients treated with radical cystectomy.

MATERIALS AND METHODS

Clinicopathological parameters of 1,643 patients (study group, SG) treated with radical cystectomy due to muscle-invasive urothelial bladder cancer were summarized in a multi-institutional database. Patients of the SG fulfilled the following conditions: clinical tumour stage T2 N0 M0 and no administration of neoadjuvant radiation or chemotherapy. Cancer-specific survival (CSS) rates were calculated referring to pathological tumour stages in cystectomy specimens (<pT2, pT2, >pT2) (mean follow-up: 51 months). Furthermore, a multivariable model integrating clinical information was developed in order to predict the probability of downstaging.

RESULTS

A total of 173 patients (10.5%) of the SG presented with downstaging in pathological tumour stages (pT0: 4.8%, pTa: 0.4%, pTis: 1.3%, pT1: 4.1%); 12 of these patients had positive lymph nodes (7%, in comparison with 21% pN+ of pT2 tumours and 43% of >pT2 tumours). Patients with tumour stages <pT2, pT2 and >pT2 had CSS rates after 5 years of 89, 69 and 46%, respectively (p<0.001). In a multivariable Cox model the presence of pathological downstaging resulted in a significant reduction of cancer-specific mortality (HR 0.30; 95% CI 0.18-0.50). By logistic regression analysis the date of TURB (benefit for more recent operations) was identified as the only independent predictor for downstaging of muscle-invasive clinical tumour stages. Age, gender, grading and associated Tis in the TURB did not reveal any significant influence.

CONCLUSION

Patients with muscle-invasive clinical tumour stages and downstaging in cystectomy specimens represent a subgroup with significantly enhanced CSS rates. Further trials that integrate the parameters tumour size, stages cT2a vs cT2b and focality are required in order to define the independent prognostic signature of downstaging of tumour stages more precisely.

[Urethral reconstructive surgery]

There is no technique which can be used in all types and localizations of urethral strictures. Urethral strictures occur in the majority of cases in the bulbar urethra. The success rate of urethroplasty is above 80% and results are much better compared to DVIU. Dorsal onlay shows a significantly better success rate than ventral onlay. If the graft bed has poor vascularization a flap should be used or a staged approach should be considered.

[Tomatoes and lycopene in prevention and therapy--is there an evidence for prostate diseases?]

Tomatoes are discussed to have an important role in the prevention of and therapy for prostate cancer (PCA). Whether or not they are also useful in the primary and secondary prevention of benign prostate hyperplasia (BPH) is not clear. This review summarises the results of original contributions with a focus on interventional studies. Whereas epidemiological studies on BPH prevention provide no evidence for a preventive potential of tomatoes and tomato products, the majority of interventional trials points to an increased DNA resistance against oxidative-induced damage. Even though their effect on a surrogate marker of the IGF pathway cannot be evaluated so far due to insufficient data, the consumption of tomatoes and tomato products may probably protect from PCA--at least when considering low-grade PCA. Thus, regular consumption of these foods can be recommended for the prevention of PCA. Tomato products might also be useful in the therapy for BPH and PCA. The intake of isolated lycopene does not protect from the development of PCA. However, in the doses achieved by consumption of tomato products, lycopene ingestion might also be effective in PCA therapy.

[Prostate cancer research. Biomarkers as promising options for optimized diagnosis and treatment]

A better understanding of signal transduction and gene regulation during prostate carcinogenesis will allow the development of novel diagnostic and prognostic biomarkers and a better prediction of the individual course of prostate cancer disease. It will also enhance the design and development of specific small molecular components aiming for specific therapies. The research groups in Bonn succeeded in the competition for an endowed professorship supported by the Rudolf Becker Stiftung (German Science Endowment Fund) settled in the"Centrum für integrierte Onkologie" funded by the German Cancer Aid. This should be the perfect breeding ground for future research in the field of prostate cancer.

[Ureterocystoplasty in the treatment of "low-compliance" bladder in children]

In cases of inadequate or insufficient conservative treatment of non-compliant bladders the function of the upper urinary tract is jeopardized. We present our experience with ureterocystoplasty as one possible treatment option.A total of eight children underwent ureterocystoplasty. The etiology of bladder non-compliance and the need for augmentation was neurogenic in five children, posterior urethral valves in two children, and in one child after repeated antireflux surgery. In all patients the kidney of the used ureter was functionless. Surgery was done through a transperitoneal approach. Following nephrectomy, the renal pelvis and the ureter were spatulated and sutured into the bladder incision. An additional MACE procedure was performed in three patients, antireflux surgery for the contralateral kidney in two patients, and one patient underwent stone removal in the remaining kidney. In one patient the ureter was used as a free transplant and was covered by an omental flap. In addition a simultaneous living donor kidney transplant was performed. The storage function could be improved in all patients. The function of the ureter which was used as a free transplant showed good clinical results. The longest follow-up is 8 years. Ureterocystoplasty is a useful and metabolically neutral alternative to bowel segments. In patients with only one functioning kidney and a contralateral megaureter, ureterocystoplasty is the treatment of choice in our institution.

Soy isoflavone genistein in prevention and treatment of prostate cancer

Dietary habits and incidence of prostate cancer (PCa) are very different in several parts of the world. Among the differences between Eastern and Western diets is the greater intake of soy in the Eastern cultures. This might be one factor contributing to a lower incidence of PCa in Asian men. Many studies using PCa cells and animal studies of chemical carcinogenesis have shown that a wide range of dietary compounds have cancer chemopreventive potential. Therefore, the interest in nutrition-based approaches for prevention and treatment of PCa is increasing. We reviewed all experimental preclinical in vitro and in vivo data as well as clinical trials performed with soy isoflavone genistein for prevention and treatment of PCa. The preclinical data for genistein presented in this review show a remarkable efficacy against PCa cells in vitro with molecular targets ranging from cell cycle regulation to induction of apoptosis. In addition, seemingly well-conducted animal experiments support the belief that genistein might have a clinical activity in human cancer therapy. However, it is difficult to make definite statements or conclusions on clinical efficacy of genistein because of the great variability and differences of the study designs, small patient numbers, short treatment duration and lack of a standardized drug formulation. Although some results from these genistein studies seem encouraging, reliable or long-term data on tumor recurrence, disease progression and survival are unknown. The presented data potentially allow recommending patients the use of genistein as in soy products in a preventive setting. However, at present there is no convincing clinical proof or evidence that genistein might be useful in PCa therapy.

[Aggressive course of a malignant alveolar soft tissue sarcoma]

Alveolar soft part sarcoma is a rare soft tissue tumor. Most patients who are affected by this sarcoma are between 15 and 35 years old. The tumor is characterized by its uncommon location of metastasis. Publications concerning this sarcoma subform are rare and the best therapeutic procedure is not yet clear. Surgical excision, radiation and chemotherapy are performed, whereas complete surgical excision achieves the best results in long-term follow-up. We report a patient's history who rapidly died of his sickness despite the low initial tumor stage.

Prostate cancer tissue is masked by bicalutamide: a case report

Prostate cancer is the most common malignant tumor in men. Recently, a slightly decreased frequency of margin positivity following neoadjuvant bicalutamide treatment due to tumor shrinkage was reported. Trials investigating other anti-androgens in the past also reported lower frequencies of surgical margin positivity, but patients outcome has not improved. In this case, local recurrence was confirmed by needle biopsy in a patient five years following radical prostatectomy for prostate adenocarcinoma. After therapy with 50 mg bicalutamide for a month, the tumour was resected. Despite of detailed histological work-up and immunohistochemistry cancer suspicious lesions were not found. We think that bicalutamide may be capable of masking prostate cancer cells.

[Primitive neuroectodermal tumor of the kidney]

Primitive neuroectodermal Tumor (PNET) is a rare malignant tumor of young adult. Patients often present with the classical trias of renal cancer (pain, haematuria, palpable tumor). Specific radiological signs are missing, and therefore a PNET is often diagnosed postoperatively. It is characterized by the expression of MIC2, neural markers (Vimentin, S-100, Synaptophysin) and EWS/FLI1-translocation. The tumor is often diagnosed in advanced stage, and prognosis is poor despite of multimodal treatment including radical nephrectomy, polychemotherapy (vincristine, adriamycin, cyclophosphamid, etoposide, ifosfamide) and radiation in case of metastases or incomplete resection of primary tumor. We represent two cases of metastatic renal PNET in a 28- and 39-year-old patient. Due to the multimodal treatment a partial and a complete remission was achieved, respectively.

GSTP1 hypermethylation as a molecular marker in the diagnosis of prostatic cancer: is there a correlation with clinical stage, Gleason grade, PSA value or age?

OBJECTIVES

Epigenetic events such as promoter hypermethylation have been implicated in prostate carcinogenesis. We present a real-time, methylation specific protocol to detect hypermethylation in the promoter region of the GSTP1 gene in benign hyperplasia and adenocarcinoma of the prostate.

METHODS

In our preliminary study, 31 prostate cancer and 5 benign prostatic hyperplasia (BPH) tissue samples were analyzed. Genomic DNA was isolated from formalin-fixed and paraffin-embedded specimens and subjected to sodium bisulfite modification, followed by real-time, methylation specific PCR. Patients with prostatic cancer were also subdivided according to their Gleason score, PSA, age and TNM Staging. Prostate cancer cell lines (LNCaP, DU145, PC3) and a BPH cell line (BPH-1) were also tested as controls.

RESULTS

GSTP1 promotor hypermethylation was detected in 28 of the 31 prostate cancer cases (90.3%) and none of the five (0%) BPH cases. Statistical analysis did not reveal a significant correlation between GSTP1 hypermethylation and Gleason score, PSA, age or TNM staging. All prostate cancer cell lines were testes positive for GSTP1 promotor hypermethylation, whereas the BPH cell line (BPH-1) was tested negative.

CONCLUSION

GSTP1 promotor hypermethylation occurs during carcinogenesis and is considered to be a major event of prostate carcinogenesis. Our data support this thesis and shows that GSTP1 hypermethylation reliably distinguishes between prostate cancer and BPH . Although it is not yet clear at what time during carcinogenesis hypermethylation of the GSTP1 promotor occurs it seems to provide valuable information for prostate cancer screening and diagnosis. Larger studies are underway to determine the potential role for GSTP1 hypermethylation in clinical settings.

In vivo platelet deposition on polytetrafluoroethylene coated with fibrin glue containing fibroblast growth factor 1 and heparin in a canine model

BACKGROUND

We previously reported that the coating of expanded polytetrafluoroethylene (ePTFE) with fibrin glue containing fibroblast growth factor 1 (FGF-1) and heparin accelerates endothelial coverage of grafts implanted into animals. We report here the effect of this surface modification on early platelet deposition.

MATERIALS AND METHODS

Nine dogs received 7-cm ePTFE grafts, 60-microns internodal distance, 4-mm internal diameter, as bilateral aortoiliac implants, one coated (luminal cross section and abluminal surface) with fibrin glue (fibrinogen 32.1 mg/mliters, thrombin 0.32 U/mliters) containing FGF-1 (11 ng/mliters and heparin (250 U/mliters), the other uncoated. After 5, 30, or 120 minutes of circulation with blood containing autologous platelets radiolabelled with indium 111, gamma emissions were quantitated on explants and correlated to surface areas measured by computerized planimetry.

RESULTS

Both global and segmental comparisons showed significantly (P < 0.05, Student's t-test) less platelet deposition on coated than on uncoated grafts after 120 minutes of circulation, but no difference at 5 and 30 minutes.

CONCLUSIONS

In this model, ePTFE coating with fibrin glue containing FGF-1 and heparin shows no adverse effect on early platelet deposition.

Biomaterial-induced macrophage activation and monokine release

This study quantifies macrophage acid phosphatase release as a marker of cell activation when cultured with or without biomaterials. Peritoneal macrophages were harvested from six New Zealand White rabbits and cultured in minimum essential media with 10% equine serum. After cell identification by morphology, nonspecific esterase, and RAM 11 immunoperoxidase, cells were passaged twice, and second-passage macrophages were seeded in 96-well plates (5,000 cells/well) and grown to confluence. After collection of day zero media, circular disks of polyglactin 910 and two types of commercially available polyethylene terephthalate with different construction and sterilization characteristics were placed on the cell monolayer. Controls without biomaterials were also established. Media was collected and pooled for each group and time point beginning on day 2 and continuing every other day for 22 days. Conditioned media were quantitatively assayed for acid phosphatase colorimetrically at 402 nm using p-nitrophenylphosphate as the substrate. Acid phosphatase activity increased progressively at late time points for each group but no difference was noted between groups at any time point. These data show that the activation of cultured macrophages with time is not altered differentially by the presence of biomaterials. The previously demonstrated monokine release following biomaterial exposure is therefore a specific event and not simply part of the generalized activation phenomenon.

Kinetics of cell proliferation as a function of vascular graft material

Bioresorbable vascular grafts constructed for polyglactin 910 (PG910) and polydioxanone (PDS) and nonresorbable Dacron were interposed into the infrarenal abdominal aortas of New Zealand White rabbits. The prosthesis/tissue complexes were harvested after 2, 3, 4, 12, and 52 weeks. Seventeen, 9, and 1 h prior to sacrifice, animals received tritiated thymidine (0.5 mCi/kg/dose). All specimens were studied grossly and by light and transmission electron microscopy. Mitotic indices (MI's) were determined by autoradiography for inner capsule myofibroblasts at the proximal, mid, and distal segments of each prosthesis. There were no aortic-related deaths. All grafts were patent with no aneurysmal dilatation. At 4 weeks, PG910 resorption was evidenced by macrophage phagocytosis, less so in PDS while Dacron remained intact. At 12 weeks, the PG910 was completely resorbed while PDS resorption continued. The latter was completely resorbed by 52 weeks. There was no significant difference in MI's between proximal, mid, and distal regions for each graft type. The mitotic index paralleled the rate of prosthetic resorption in both PG910 and PDS groups, as high as 28.34 +/- 23.21 in the former 3 weeks after implantation and significantly higher at 4 weeks (7.58 +/- 2.02 and 7.50 +/- 2.66, respectively) than at 52 weeks (0.72 +/- 0.98 and 1.00 +/- 0.22, respectively) in both groups. The mitotic index in the Dacron group never surpassed 1.22 +/- 0.90. We conclude that higher levels of early cell proliferation in bioresorbable grafts closely parallel the kinetics of prosthetic resorption.

The effects of an atherogenic diet on macrophage/biomaterial interactions

We previously reported that biomaterials differentially induced macrophages to secrete growth factors that mediate reendothelialization. The present study evaluates the effect of an atherogenic diet on macrophage/biomaterial interactions. Female New Zealand white rabbits were fed an atherogenic diet. Peritoneal macrophages were harvested from these as well as rabbits fed a normal diet and cultured in Minimum Essential Medium with platelet-poor serum. Dacron or polyglactin 910 were added to two of three conditions of both cell groups in passage 2. Conditioned media were collected weekly through week 15. Mitogenicity assays were performed with quiescent mouse embryonal (BALB/c3T3) fibroblasts, atherosclerotic rabbit aortic smooth muscle cells, and murine capillary lung (LE-II) endothelial cells. Mitogenic activity was assayed by scintillation counting of tritiated thymidine incorporation into deoxyribonucleic acid (DNA). Results showed increased mitogenic activity released by macrophages from atherosclerotic rabbits, in the absence of prosthetic material, when assayed against every cell line. In normal diet macrophages, polyglactin 910 stimulated mitogen release for every cell line, and Dacron yielded minimal mitogen release. In lipid diet macrophages polyglactin 910 slightly increased mitogen release for all three cell lines, whereas Dacron resulted in stimulation of DNA synthesis in smooth muscle cells and BALB/c3T3 cells but less DNA synthesis in LE-II cells than in control, no graft material, media. Western blotting demonstrated immunoreactivity to basic fibroblast growth factor in media from normal diet macrophages but only in the presence of polyglactin 910 or Dacron. Radioimmunoassay for platelet-derived growth factor B chain was negative in all groups, and polymerase chain reaction techniques to amplify transforming growth factor-beta messenger ribonucleic was negative. These data demonstrate the effect of in vivo dietary manipulation on macrophage activation as well as the effect of an atherogenic diet in modulating macrophage/biomaterial interactions. Additionally, different biomaterials differentially induce macrophages to release factors that stimulate and inhibit growth.

Kinetics of collagen deposition within bioresorbable and nonresorbable vascular prostheses

This study compares the kinetics of collagen deposition within the prosthesis/tissue complexes formed following implantation of either polyglactin 910 (PG910), polydioxanone (PDS), or Dacron prostheses into rabbit infrarenal aortas. The grafts were explanted in triplicate at 1, 3, and 12 months, and then processed for spectrophotometric hydroxyproline quantitation. A 2 mm longitudinal strip from each sample was processed for histologic evaluation by light and electron microscopy. Results showed more extensive collagen deposition within the prosthesis/tissue complexes of both PG910 and PDS continuing throughout 3 months, as compared to less collagen deposition in Dacron grafts at all time points. Differences between PG910 and Dacron, and between PDS and Dacron at each time point were statistically significant. When correlated with previous related studies done in our laboratory, data showed that in resorbable grafts the rate of collagen deposition parallels the kinetics of cellular proliferation, tissue thickening, and graft resorption.

The validity of canine platelet aggregometry in predicting vascular graft patency

Several laboratories have found canine platelet aggregometry predictive of thrombotic potential in vascular grafts. Adenosine diphosphate (ADP) is a frequently used agonist, often at unspecified or differing concentrations. This study was designed to evaluate the predictive value of ADP-induced platelet aggregometry and the validity of the methodology. Platelet aggregometry in response to 2 x 10(-5) M ADP was assayed in 70 dogs. Twenty-six percent were aggregators, 51% were non-aggregators, and 20% were indeterminant. All dogs were then treated with aspirin and dipyridamole. Vascular prostheses were implanted bilaterally (aorto-iliac) and anti-platelet therapy continued for two weeks. Dose-response to ADP was studied at three concentrations in 20 dogs. At 2 x 10(-5) 1/20 aggregated, at 4 x 10(-5) 3/19 aggregated and at 2 x 10(-4) 15/20 aggregated. Time between samples and study was evaluated in 11 dogs, with 2/11 changing from non-aggregator to aggregator at two or three hours. Daily reproducibility was studied in 70 dogs, 14 of which changed aggregation status between days. Patency was 58/68 (85%) for non-aggregators, 23/34 (68%) for aggregators (p = 0.038). Platelet aggregometry has significant predictive value for graft patency but methodology must be specified and standardized.

Prostacyclin production by blood-contacting surfaces of endothelialized vascular prostheses

This study examines prostacyclin production by blood-contacting surfaces within woven vascular prostheses of polydioxanone (PDS), polyglactin 910 (PG910), or Dacron interposed into rabbit infrarenal aortas. Grafts and normal aortic segments were explanted after 1, 3, and 6 months for pulsatile perfusion with Medium-199 for 60 minutes. Aliquots were removed serially for 6-keto-PGF1 alpha assay. After 30 minutes sodium arachidonate (10 micrograms/ml) was added. Specimens were studied by light microscopy, SEM and TEM. Patency in all three groups exceeded 90%. All three showed re-endothelialization at one month. Normal aorta produced low basal 6-keto-PGF1 alpha with a marked evanescent post arachidonate increase. Dacron did not differ from normal aorta. PG910 and PDS both produced significantly less 6-keto-PGF1 alpha post arachidonate at one month but both increased to normal by three months.

Plasma polymerized tetrafluoroethylene/polyethylene terephthalate vascular prostheses

Tetrafluoroethylene (TFE) was discharged onto woven polyethylene terephthalate (PET) prostheses, and the PET prostheses (50 mm long) with or without TFE were implanted into canine carotid arteries and aortas. Additional controls included polytetrafluoroethylene and Dacron. Specimens were explanted after one to 12 months, photographed, and sectioned for light and scanning and transmission electron microscopy, and thrombus-free surface areas calculated by computerized planimetry. Results showed no significant patency differences among carotid or aortic groups. However, both PET carotid groups had significantly greater thrombus-free surface areas. Histologically, both PET groups appeared identical. An endothelialized neointima covered PET carotid specimens by six months, compared with three months in the aortic position, with greater pannus ingrowth in both PET groups. Plasma polymerized TFE offered no additional advantage in these long-term experiments.

Platelet interactions with heparin binding growth factor and fibronectin

A fibronectin (Fn)/heparin/heparin binding growth factor (HBGF)/heparin (FHHH) complex can be affixed to vascular grafts. This study examines the effect of HBGF, Fn, and FHHH on platelet adhesion and aggregation. Expanded polytetrafluoroethylene (PTFE) grafts (5 cm X 4 mm) were treated with Fn (n = 9), FHHH (n = 9), or neither (n = 10) and interposed into canine aortoiliac systems, using each dog as its own control. Autogenous radiolabeled (111In oxine-650 muCi) platelets were injected IV prior to re-establishment of circulation. Blood flow was determined by electromagnetic flowmetry and perfusion maintained for 30 min. Grafts were removed with native aorta and ipsilateral iliac arteries (IIA). Specimens, excluding anastomoses, were sectioned for gamma counting and computerized planimetry. Results showed that FHHH and Fn treated grafts contained significantly more radioactivity than control segments, when normalized to their IIA. FHHH treated grafts contained 27 +/- 16 times more radioactivity per mm2 than IIA, Fn treated prostheses 12 +/- 8 times more, and untreated PTFE 4 +/- 3 times more. FHHH was significantly more radioactive than Fn alone (p less than or equal to 0.03). Platelet aggregation in response to either Fn or HBGF was studied in vitro. Aggregation was not activated by either Fn (1-100 micrograms/100 microliters) or HBGF (25-2,500 ng/100 microliters). These data suggest that Fn and HBGF promote platelet adhesion but not aggregation.

Macrophage/biomaterial interactions: the stimulation of endothelialization

This current study analyzed macrophage/biomaterial interactions as modulators of endothelial cell proliferation. Rabbit peritoneal macrophages were harvested and seeded (1 x 10(6) cells/ml) into culture flasks with Dulbecco's modified Eagle medium and 10% platelet-poor, plasma-derived equine serum. Macrophages were identified by morphologic characteristics, nonspecific esterase, and Fc (immunoglobulin G) receptors on the cell membranes. Culture conditions were (1) no prosthetic material, (2) Dacron, or (3) Polyglactin 910 (PG910) (Ethicon, Inc., Somerville, N.J.). Both prosthetic materials were finely shredded into the media. After 5 weeks in culture, PG910 inclusions were seen within macrophage cytoplasm. No intracytoplasmic Dacron was observed. Conditioned media from all three groups were collected weekly from week 5 to week 10, centrifuged, filtered, and added in serial dilutions to cultured quiescent murine capillary lung endothelial cells. Quiescence was achieved by serum deprivation and verified by [3H]thymidine incorporation. Sixteen hours after addition of conditioned media, [3H]thymidine was measured in and expressed as percent increase above quiescent levels. Mitogenic activity in the PG910 group progressively increased from weeks 6 to 10. At week 10, the PG910 group (1:10 dilution) yielded a 620% increase in DNA synthesis. The Dacron group never varied from the control group (no prosthetic). The mean increases in [3H]thymidine incorporations over weeks 7 to 10 were PG910, 540% +/- 65%; Dacron, 323% +/- 65%, and control, 343% +/- 26% (PG910 vs Dacron, p less than or equal to 0.004). These studies suggest macrophage activation by bioresorbable prostheses, yielding growth factor release with subsequent enhanced endothelial cell proliferation.

Hemodynamic effects on endothelial cell monolayer detachment from vascular prostheses

The establishment of an early blood-contacting endothelialized surface may improve the graft-host relationship. This study evaluated the adherence of indium 111-radiolabeled endothelial cells that were cultured to confluence on fibronectin-treated polyester elastomer (Hytrel) grafts that were perfused for two hours on a pulse duplicator apparatus under high- and low-shear conditions. Perfusate samples were serially assayed for radioactivity. After perfusion, grafts were sectioned into four segments and assayed for retained radioactivity. All graft segments were hematoxylin stained and examined under light microscopy for evaluation of cell density. Excellent endothelial cell adherence (90%) was observed under both hemodynamic conditions at 120 minutes, with most losses occurring within the first 15 minutes. No differences were seen between high- and low-shear conditions or proximal vs distal graft segments.

Derivation of neointima in vascular grafts

Vascular prostheses woven from absorbable lactide/glycolide copolymers are replaced by myofibroblast-laden tissue conduits lined by endothelium. When these prostheses are implanted in arteries of animal models, the absorption-replacement reactions are inhibited by Dacron. To determine whether these reactions resulted primarily from transanastomotic pannus ingrowth, prostheses (30 mm x 4 mm) were constructed of three 10-mm long segments with Dacron segments on both ends and a middle polyglactin 910 (PG910) segment. The prostheses were implanted in the aortas of 15 adult New Zealand White rabbits. Resultant prosthesis/tissue complexes were harvested in triplicate at 2 weeks and at 1, 2, 3, and 4 months after implantation. Explants were photographed and sectioned for light microscopy and for scanning and transmission electron microscopy, which showed 100% patency with no aneurysms or stenoses. Inner-capsule thickness in the PG910 segments increased only during the interval from 2 weeks to 2 months; this thickness was statistically greater than either Dacron segment at 1 and 2 months (p less than or equal to 0.004 and p less than or equal to 0.0001, respectively). Proximal and distal Dacron segments did not differ from each other in thickness. Inner capsules of PG910 segments at 1 month were composed predominantly of myofibroblasts, whereas inner capsules of Dacron segments were composed of fibrin coagulum beyond the initial 2 mm of endothelial pannus ingrowth. These data suggest that transanastomotic pannus ingrowth is not the primary source of cells replacing absorbable vascular prostheses.

Polyglactin 910/polydioxanone bicomponent totally resorbable vascular prostheses

Previous studies from our laboratory have shown that bioresorbable vascular prostheses woven from lactide-glycolide copolymers and implanted into arteries of several animal models become replaced by cellular tissues; the rate of replacement parallels the kinetics of prosthetic resorption. This study evaluates the efficacy of bicomponent resorbable prostheses as a method of augmenting resistance to dilatation during the resorption period of the more rapidly resorbed component. Bicomponent prostheses (n = 37) were woven from compound yarns containing 74% polyglactin 910 (PG910) and 26% polydioxanone (PDS) and were interposed into adult white New Zealand rabbit infrarenal aortas. Resultant prosthesis-tissue complexes were harvested after 2 weeks to 12 months. Specimens were photographed and sectioned for light, scanning, and transmission electron microscopy. Randomly selected fresh explants at 1 and 3 months and control aortic segments from the same rabbits were simultaneously perfused with culture media (37 degrees C, 100/80 mm Hg, 60 ml/min) and perfusates assayed by means of tritiated radioimmunoassay techniques for the stable prostacyclin metabolite 6-keto-PGF1 alpha before and after the addition of sodium arachidonate (10 micrograms/ml) to the media. Results showed 100% patency, no aneurysms, and stenosis in 1 of 37 prostheses (3%). PG910 was totally resorbed by 2 months and PDS by 6 months. By 1 month inner capsule thickness was 303 +/- 30 microns. In contrast to previous reports this was significantly thicker than that within 100% PDS (230 +/- 40 microns) and significantly less thick than in 100% PG910 (530 +/- 62 microns). Inner capsules in all three groups stabilized at similar thicknesses (417 to 502 microns).(ABSTRACT TRUNCATED AT 250 WORDS)

Arterial regeneration over polydioxanone prostheses in the rabbit

We analyzed histologic, ultrastructural, and functional characteristics of rabbit aortic conduits regenerated over absorbable polydioxanone prostheses. Twenty-eight polydioxanone-elicited prosthesis/tissue complexes harvested two weeks to 12 months following implantation were analyzed grossly; photographed; sectioned for light, scanning, and transmission electron microscopy; and studied for compliance, bursting strength, and prostacyclin and thromboxane metabolite contents. No aortic-related deaths or hemorrhages occurred. Smooth regenerated conduits without stenoses were seen in 27 of 28 specimens, with one small aneurysm. Transprosthetic myofibroblast migration and proliferation paralleled the kinetics of macrophage-mediated prosthetic dissolution, which was consequently delayed compared with polyglycolic acid prostheses. Confluent endothelial-like luminal surfaces were present after two weeks. Progressive inner capsular thickening ended after three months at 420 micron. Ex vivo compliance curves resembled arterial elasticity. Regenerated tissue withstood 1200 mm Hg of systolic pressure, and 6-keto-prostaglandin F1 alpha to thromboxane B2 ratios did not differ from normal control specimens.

Compound polyglactin 910/polypropylene small vessel prostheses

This study evaluated morphologic and functional characteristics of tissue reactions to compound prostheses of 69% absorbable polyglactin 910 (PG910) and 31% nonabsorbable polypropylene in the rabbit. Forty-two woven PG910/polypropylene prostheses (24 X 4 mm internal diameter) implanted into rabbit infrarenal aortas were harvested after 2 weeks to 12 months. Each explant was photographed and sectioned for light microscopy and transmission and scanning electron microscopy. Randomly selected explants underwent either compliance and bursting strength measurements or assays of production of prostacyclin and thromboxane metabolites by luminal surfaces of both regenerated conduits and normal control aortas in response to administered sodium arachidonate. Results showed 100% patency with no aneurysms and 2% stenoses (1 of 42 prostheses). Confluent endothelial-like cellular luminal surfaces covering oriented smooth muscle-like myofibroblasts comprised the inner capsules whose thicknesses stabilized at 1 to 2 months. Only residual polypropylene remained in the prostheses after 2 months. Compliance studies reflected a 0.65 mm (14%) change over a pressure range of 0 to 160 mm Hg. All regenerated prosthesis-tissue complexes had bursting strengths greater than the proximal perianastomotic native aortas, which burst between 600 and 2000 mm Hg. At 1 month the rate of production of 6-keto-PGF1 alpha per square millimeter of surface area of experimental segments was normal. Production of 6-keto-PGF1 alpha by experimental segments at 3 months had increased fourfold whereas thromboxane B2 (TxB2) production remained unchanged. The 6-keto-PGF1 alpha/TxB2 ratio increased from 1 to 4 months. This study demonstrates clinically efficacious morphologic, mechanical, and biochemical characteristics of PG910/polypropylene-elicited vascular prosthesis-tissue complexes.

Biomaterial pretreatment with ECGF to augment endothelial cell proliferation

ECGF, a polypeptide of bovine hypothalamic derivation, is the most potent endothelial cell mitogen known, with mitogenic and chemotactic effects well demonstrated in vitro on human endothelial cells. These effects are synergized by heparin. In vivo re-endothelialization of blood-contacting biomaterials may be enhanced by bonding ECGF and heparin to prosthetic surfaces. Long woven Dacron (24 mm) and woven PDS vascular prostheses were treated first with human plasma fibronectin (10 micrograms/cm2). Porcine sodium heparin (20 micrograms/cm2) was added by means of fibronectin's heparin affinity. Pure 125I-ECGF (95% alpha, 5% beta; 1 ng/cm2) was next fixed by the heparin affinity of ECGF and followed by a second heparin layer (20 micrograms/cm2) to synergize with and stabilize ECGF. 125I-ECGF adherences were determined by scintillation counts. Attachment efficiency averaged 25%. Prostheses were interposed into rabbit aortas and harvested in triplicate from 0 to 30 days to establish in vivo washout curves. After explantation, residual 125I-ECGF was eluted from prostheses, and intact ECGF was identified by SDS gel electrophoresis. Similarly prepared but nonradioiodinated Dacron and PDS prostheses were explanted after 7 days and their ECGF eluted off for in vitro activity documentation. This ECGF retained its mitogenic properties, causing a 1000% to 1200% increase in 3H-thymidine incorporation into newly synthesized DNA in test murine LE-II cells. Fibronectin-heparin-ECGF fixation to blood-contacting biomaterials may enhance spontaneous re-endothelialization and/or hasten the confluence of transplanted endothelial cells.

Dacron inhibition of arterial regenerative activities

These biocompatibility studies evaluate the effects of Dacron, absorbable polymeric, and compound prostheses containing both elements in various constructions on the migration, proliferation, and functional characteristics of regenerating endothelial and smooth muscle-like cells in the rabbit aorta model. Prosthesis/tissue complexes explanted after 2 weeks to 9 months were studied grossly, photographed, sectioned for light microscopy and scanning and transmission electron microscopy, and assayed for 6-keto-PGE1 alpha contents in inner capsular tissues. Polyglycolic acid, polyglactin 910, or polydioxanone prostheses elicited a transinterstitial migration and proliferation of primitive mesenchymal cells that differentiated into smooth muscle-like myofibroblasts and a surface repopulation of confluent endothelial-like cells paralleling the time course of macrophage-mediated prosthetic dissolution. Even small Dacron components (20%) woven into or surrounding the absorbable polymer significantly inhibited these processes, yielding significantly thinner, less cellular inner capsules with lower 6-keto-PGF1 alpha contents. These studies show the augmentation of clinically efficacious arterial regenerative activities by polymers phagocytosed by macrophages and the inhibition of these activities by Dacron.

Morphological evidence of the shedding of chondrocytes from the articular surface in neonatal rats: relationship to the interlacunar network

The superficial zone of the femoral head articular cartilage of 5- to 15-day old rats was examined by light and electron microscopy for evidence of shedding into the joint space. Chondrocytes deepest in the superficial zone were round, surrounded by a capsule, and connected to adjacent chondrocytes by the interlacunar network, whereas cells in the middle of the zone appeared similar but with less cytoplasm. At the circular surface, chondrocytes were small, with pyknotic nuclei and poorly defined organelles. These cells occasionally protruded from the articular surface but maintained at least partial connection with the network and their capsule. Depressions in the articular surface were lined with material similar to that of the network and were the only locations found where the network did not terminate at a cell surface. This static evidence suggested at least two hypotheses: 1) Degenerating chondrocytes moved up through the superficial zone to the articular surface and were shed into the joint space. This movement may be facilitated by the network as part of neonatal cartilage development. 2) During joint formation, the surface of the articular cartilage was eroded down to the chondrocytes, which were exposed to the joint fluid, causing cell degeneration, death, and shedding. Evidence of cell shedding was rarely seen after 2 weeks of age. Likewise, the interlacunar network disappeared from the superficial zone during this period. A physiological as well as structural relationship may exist between the chondrocytes and interlacunar network.

Glycol methacrylate in light microscopy: nucleic acid cytochemistry

Techniques utilizing Feulgen, azure B bromide, methyl green-pyronin, gallocyanin chromalum and cresyl violet stains have been modified and adapted for visualizing nucleic acids in 0.5-2.0 micrometer sections of tissues embedded in glycol methacrylate (GMA). Methods for evaluating the stain specificity for DNA and RNA using deoxyribonuclease and ribonuclease digestions, aldehyde blocking, and acid extractions are also described. The specificity of the stains in GMA embedded tissues is comparable to that reported for paraffin-embedded tissues.