2-deoxy-2[F-18] fluoro-D-glucose positron emission tomography Deauville scale and core-needle biopsy to determine successful management after six doxorubicin, bleomycin, vinblastine and dacarbazine cycles in advanced-stage Hodgkin lymphoma.

BACKGROUND: The clinical impact of the positivity of the Deauville scale (DS) of positron emission tomography (PET) performed at the end of doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD) in patients with advanced Hodgkin lymphoma (HL), in terms of providing rationale to shift poor responders onto a more intensive regimen, remain to be validated by histopathology. PATIENTS AND METHODS: This prospective trial involved patients with stage IIB/IV HL who after six ABVD cycles underwent PET (PET6) and core-needle cutting biopsy (CNCB) of 2-deoxy-2[F-18] fluoro-d-glucose (FDG)-avid lymph nodes. Patients received high-dose chemotherapy/autologous haematopoietic stem cell rescue (HDCT/AHSCR) if CNCB was positive for HL, alternatively, if CNCB or PET was negative, received observation or consolidation radiotherapy (cRT) on residual nodal masses, as initially planned. The end-point was 5-year progression-free survival (PFS). RESULTS: In all, 43 of the 169 (25%) evaluable patients were PET6 positive (DS 4, 32; DS 5, 11). Among them, histology showed malignancy (HL) in 100% of DS 5 scores and in 12.5% of DS 4 scores. Fifteen patients with positive biopsy received HDCT/AHSCR, whereas 28 patients with negative biopsy, as well as 126 patients with negative PET6, continued the original plan (cRT, 78 patients; observation, 76 patients). The 5-year PFS in the negative PET6 group, negative biopsy group and positive biopsy group was 95.4%, 100% and 52.5%, respectively. CONCLUSION: DS positivity of end-of-ABVD PET in advanced HL carried a certain number of CNCB-proven non-malignant FDG-uptakes. The DS 4 scores which were found to have negative histology appeared to benefit from continuing the original non-intensive therapeutic plane as indicated by the successful outcome in more than 95% of them by obtaining similar 5-year PFS to the PET6-negative group. By contrast, the DS 5 score had consistently positive histology and was associated with unsuccessful conventional therapy, promptly requiring treatment intensification or innovative therapeutic approaches.

Is 2-deoxy-2-[(18)F]fluoro-D-glucose PET/CT acquisition from the upper thigh to the vertex of skull useful in oncological patients?

AIM: To assess whether performing routinely 2-deoxy-2-[(18)F]fluoro-D-glucose PET/CT ((18)FDG PET/CT) scan from the upper thigh to the vertex of skull is clinically relevant. MATERIALS AND METHODS: 3502 (1634 female; mean-age 60+16) consecutive patients undergoing (18)FDG PET/CT were retrospectively analyzed. Patients were divided in 10 groups according to primary malignancy. Chi-square analysis was used to assess differences among proportions. A p value < 0.05 was considered significant. RESULTS: (18)FDG PET/CT was positive in head district in 130/3502 (3,7%) patients. In all patients lesions were unknown before PET/CT examination. PET/CT showed 158 positive brain/head uptake in the 130 patients. The 158 lesions were localized in: brain (43/158; 27%), bone (52/158; 33%), lymph node (1/158; 0,6%), soft tissue (55/158; 35%) and other sites (7/158; 4,4%). According to each group, patients were positive in the head district in 1.0% for Gastrointestinal Cancer (7/690), 3.0 % for Genitourinary Cancer (3/101), 3.7 % for Haemathologic Cancer (59/1590), 2.7 % for Gynaecologic Cancer (3/112), 7.8% for Head-Neck-Thyroid and Parathyroid Cancer (26/331), 3.5% for Breast Cancer (7/200), 2.6% for Lung Cancer (7/271), 3.4% for Melanoma (2/59), 7.4% for Sarcoma (2/27), 11.6% for Unknown Primary Tumour (14/121). CONCLUSION: Our data show a relatively high incidence of brain/head lesion in patients with Unknown Primary Tumour.

PET/CT in cancer research: from preclinical to clinical applications.

The identification of genetic and biochemical mechanisms underlying tumor growth and progression along with the unraveling of human genoma provided a plethora of new targets for cancer detection, treatment and monitoring. Simultaneously, the extraordinary development of a number of imaging technologies, including hybrid systems, allowed the visualization of biochemical, molecular and physiological aberrations linked to underlying mutations in a given tumor. In vivo evaluation of complex biological processes such as proliferation, apoptosis, angiogenesis, metastasis, gene expression, receptor-ligand interactions, transport of substrates and metabolism of nutrients in human cancers is feasible using PET/CT and radiolabeled molecular probes. Some of these compounds are in preclinical phases of evaluation whereas others have been already applied in clinical settings. Here we provide prominent examples on how some biological processes and target expression can be visualized by PET/CT in animal tumor models and cancer patients for the noninvasive detection of well-known markers of tumor aggressiveness, invasiveness and resistance to treatment and for the evaluation of tumor response to therapy.

Nuclear imaging in cancer theranostics.

The combination of a diagnostic test with a therapeutic entity is termed theranostics. The diagnostic test aims at identifying patients who will likely benefit from a specific therapeutic intervention, fail to respond or eventually manifest side effects to a given drug. The appropriate selection of patients for innovative therapies would promote an enrichment of patient population that can potentiate clinical trials and, eventually, accelerate the drug development process. For these reasons, many drug companies adopted a theranostic approach as a new and promising avenue for drug development. From an historical perspective, the concepts underlying the theranostic strategy are well known in nuclear medicine and constituted the basis of many nuclear imaging procedures currently used in clinical practice. Nevertheless the adoption of these concepts by regulatory authorities is a real progress and reflects the remarkable advances in the development of drugs against molecular targets. In this respect, the oncological field provides the strongest evidence of the clinical need to link diagnostics to therapeutics. Here, we review the contribution that non-invasive nuclear imaging may give to cancer theranostics and report prominent examples of nuclear imaging procedures that can be coupled to specific therapies. The main focus lies on imaging procedures that can identify patients who will benefit from molecularly targeted therapy or are going to fail to respond to standard treatment.

Washout of [99mTc] sestamibi in predicting response to chemotherapy in patients with multiple myeloma.

AIM: Technetium-99m 2-methoxy-isobutyl-isonitrile ([99mTc] MIBI) has been successfully used to study patients with multiple myeloma (MM). This tracer is also a substrate for P-glycoprotein (Pgp). Since Pgp overexpression is one of the primary mechanisms of multidrug resistance in MM, the aim of this study was to test whether [99mTc] MIBI could be an index of Pgp overexpression and function in MM and therefore predicts response to chemotherapy. METHODS: Forty patients with MM (12 in stage I, 15 in stage II, and 13 in stage III) showing diffuse bone marrow [99mTc] MIBI uptake were included in the study. All patients underwent whole body scintigraphy at 10 and 60 minutes after i.v. injection of 555 MBq of [99mTc] MIBI. [99mTc] MIBI washout was measured, after decay correction, as: (10 minute counts/pixel minus 60 minute counts/pixel) divided by 10 minute counts/pixel, computed on a region of interest drawn on the thoracic spine (posterior projection), taking care of avoiding heart and splanchnic organs. Disease restaging was performed at a mean time of 32+/-20 months, and patients were considered to be in remission (complete or partial) or to show disease progression on the basis of a complete clinical and hematological evaluation. RESULTS: Patients showing disease progression at restaging (n=26) had higher washout (19.3+/-9.8% vs 12.8+/-6.9%, p<0.05) than patients in remission (n=14). Disease free survival was significantly better in patients with lower washout of [99mTc] MIBI. No differences in therapeutic regimen and stage of disease at admission were found between the 2 groups. When patients treated with melphalan were excluded from the analysis, 87.5% of patients in remission had low washout. CONCLUSIONS: The present study suggests a potential role of [99mTc] MIBI washout in predicting response to chemotherapy in patients with MM.

Sentinel lymph node identification in breast cancer patients.

PURPOSE: To evaluate the predictive value of sentinel lymph node biopsy versus axillary node dissection on lymph node status in patients with T1-T2 breast cancer. MATERIAL AND METHODS: Twenty-nine patients with T1 and 12 with T2 breast carcinoma and clinically N0 axillary lymph nodes, underwent lymphoscintigraphy following the administration of 99mTc-human albumin nanocolloids. The tracer was injected subdermally, over the tumor mass, in the 34 patients with palpable lesions and peritumorally (n=3) or intratumorally (n=4), under stereotactic or ultrasound guidance, in the 7 patients with non-palpable lesions. Anterior and lateral planar images were acquired 15 min after the injection of the tracer and repeated every 30 min up to 3 hr until identification of sentinel lymph node. At the end of the scintigraphic study, sentinel node skin projection was marked using a dermographic pen. Eighteen hours after lymphoscintigraphy, sentinel lymph node was identified and removed during surgery by hand-held gamma probe, then, the remaining axillary lymph nodes were dissected. All surgical specimens underwent histologic examination. Sentinel lymph nodes free of metastasis at histology, underwent additional examination with immunohistochemistry using monoclonal antibodies against cytokeratin and EMA to search for micrometastases. RESULTS: Sentinel lymph node was identified in the 34 patients injected subdermally and in the 3 patients injected peritumorally, while it remained undetected in the 4 patients injected intratumorally except for one case in which it was isolated by radioguided surgery but not scintigraphically. Sentinel nodes resulted free of metastases both at histology and immunohistochemistry in 32 cases and metastatic in 6. In the 32 patients with non-metastatic sentinel lymph nodes the other axillary nodes were also free of metastases. Among the 6 metastatic sentinel lymph nodes, in 3 cases they were the only metastatic nodes of the axilla while in the other 3 cases metastases were spread to other axillary nodes. CONCLUSIONS: In agreement with previous studies, our results showed that sentinel lymph node radioguided biopsy is a simple and reliable method for predicting axillary lymph nodes status and for avoiding axillary dissection in early breast cancer patients with sentinel node free of metastases.

Bone marrow uptake of 99mTc-MIBI in patients with multiple myeloma.

In a previous study, we showed the ability of technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) scan to identify active disease in patients with multiple myeloma (Eur J Nucl Med 1998; 25: 714-720). In particular, a semiquantitative score of the extension and intensity of bone marrow uptake was derived and correlated with both the clinical status of the disease and plasma cell bone marrow infiltration. In order to estimate quantitatively 99mTc-MIBI bone marrow uptake and to verify the intracellular localization of the tracer, bone marrow samples obtained from 24 multiple myeloma patients, three patients with monoclonal gammopathy of undetermined significance (MGUS) and two healthy donors were studied for in vitro uptake. After centrifugation over Ficoll-Hypaque gradient, cell suspensions were incubated with 99mTc-MIBI and the uptake was expressed as the percentage of radioactivity specifically retained within the cells. The cellular localization of the tracer was assessed by micro-autoradiography. Twenty-two out of 27 patients underwent 99mTc-MIBI scan within a week of bone marrow sampling. Whole-body images were obtained 10 min after intravenous injection of 555 MBq of the tracer; the extension and intensity of 99mTc-MIBI uptake were graded using the semiquantitative score. A statistically significant correlation was found between in vitro uptake of 99mTc-MIBI and both plasma cell infiltration (Pearson's coefficient of correlation r=0.69, P<0.0001) and in vivo score (Spearman rank correlation coefficient r=0.60, P<0.01). No specific tracer uptake was found in bone marrow samples obtained from the two healthy donors. Micro-autoradiography showed localization of 99mTc-MIBI inside the plasma cells infiltrating the bone marrow. Therefore, our findings show that the degree of tracer uptake both in vitro and in vivo is related to the percentage of infiltrating plasma cells which accumulate the tracer in their inner compartments.

Coordinate up-regulation of Sp1 DNA-binding activity and urokinase receptor expression in breast carcinoma.

The regulatory mechanisms underlying the overexpression of urokinase-type plasminogen activator (uPA) and its receptor (uPAR) in highly invasive breast carcinomas remain poorly understood. In this study, we have simultaneously determined the level of uPAR and the activity of the transcription factor Sp1 in 14 breast carcinomas and 5 benign lesions. We found that uPAR levels and Sp1-binding activity are coordinately elevated in malignant tumors (r, 0.94; P < 0.001). On the contrary, undetectable or only barely detectable levels of uPAR and Sp1 activity were found in benign breast lesions. Finally, the engagement of uPAR by catalytically inactive uPA in the MDA-MB-231 breast carcinoma cell line results in a rapid up-regulation of Sp1-binding activity followed by an increase of uPAR protein. These results, taken together, suggest the existence of a uPA-dependent positive regulatory loop that may progressively enhance malignant breast cell invasiveness.

Lymph node mapping and sentinel lymph node biopsy for evaluation of axillary lymph node status in early invasive breast cancer. Our experience.

The Authors show their preliminary experience with the sentinel lymph node biopsy (SLNB) in clinical early invasive breast cancer (T1N0). During a period of 15 months, forty-two patients were submitted to SLNB upon Tc99-colloid albumin injection and SLN identification by lymphoscintigraphy. The middle number of lymph nodes found in the SLNB was 1 (1-3), whereas the middle number of lymph nodes identified in level I/II ALND specimens was 15. The SLN was identified with success in all cases (100%). The axilla was positive for metastasis in 4/42 cases. The SLN was positive in all four cases in which nodal metastasis was identified. The negative predictive value of SLN was 100%. The SLN was the only site of metastasis in 3/4 cases. The SLN pathological status accurately reflected the lymphatic basin status, but further investigation is needed to define the optimal timing of colloid injection and method of examination of the SLN.

99mTc-monoclonal antibody radiolabeled via hydrazino nicotinamide derivative for imaging disialoganglioside G(D2)-positive tumors.

3F8 is a murine IgG3 monoclonal antibody (MAb) selective for the ganglioside G(D2). Previous studies using 131I-3F8 have shown great potential in the imaging of neuroectodermal tumors and the therapy of human neuroblastoma. 131I is commonly used in radioimmunodiagnosis, but its relatively long half-life (8 days) and its high energy gamma-emission (364 KeV) are suboptimal for imaging purposes when compared with 99mTc (6 h and 140 KeV, respectively). To label 3F8 with 99mTc, the antibody was first coupled with a heterobifunctional linker, succinimidyl-6-hydrazinonicotinate hydrochloride (SHNH), obtaining a hydrazinonicotinamide-antibody conjugate. Using 99mTc-Tricine as the precursor complex, 3F8-SHNH was coupled efficiently to 99mTc, resulting in >90% radiometal incorporation, with a specific activity >10 mCi/mg and retaining full immunoreactivity. Immunoscintigraphy at 6, 22, and 46 h after intravenous injection of 1 mCi of 99mTc-3F8 showed selective neuroblastoma localization in xenografted nude mice, comparable to that obtained with the injection of 100 microCi of 131I-3F8. Biodistribution studies of 131I-3F8 and 99mTc-3F8 in mice demonstrated comparable %ID/g uptake in tumor (with a T/B ratio: approximately 2.5 at 24 h and approximately 3.5 at 48 h) and normal organs, including blood, except for spleen and liver which had about a three times higher uptake of the 99mTc conjugate. In conclusion, 99mTc can be coupled conveniently at high specific activity to 3F8 without compromising immunoreactivity. SHNH appears to be a useful linker for 99mTc in tumor diagnostic imaging and may have potential utility in coupling other radioisotopes (e.g., 94mTc) for positron imaging and therapy.

Measurement of P-glycoprotein expression in human neuroblastoma xenografts using in vitro quantitative autoradiography.

P-glycoprotein (P-gp) has a role in multidrug resistance (MDR) encountered in human cancers. In this study, we used the colchicine-resistant cell line BE(2)-C/CHCb(0.2), a strain of neuroblastoma cell line BE(2)-C, as a model to measure variations of P-gp expression in cells grown in vitro and in vivo. Cells were cultured in the medium supplemented with colchicine. At the beginning of the study the drug was withdrawn and, after 22 days, added back to the culture medium. Cells were harvested at various time points and xenografted in nude mice. P-gp content in cells was measured by self-competitive binding assay and in tumors, by quantitative autoradiography (QAR). Both assays were carried out using 125I-labeled monoclonal antibody MRK16, reactive with P-gp. Concentration of P-gp in cells varied from a maximum of 1,361 pmol/g in the presence of colchicine to a minimum of 374 pmol/g in the absence of colchicine in the culture medium. P-gp concentration in the tumors ranged from 929 to 188 pmol/g, which correlated with P-gp content in the cells at the time of their injection in the mice. QAR is an accurate and reliable method to quantify P-gp expression in tumors. Changes in colchicine concentration in the ambient medium of BE(2)-C/CHCb(0.2) cells growing in vitro resulted in a change in phenotype of P-gp expression, which was stable under conditions of in vivo growth over approximately 9 cell divisions in nude mice xenografts. Therefore, P-gp content in xenografts depends only on the level of resistance of the cells at the time of their injection in the mice.

Detection of focal myeloma lesions by technetium-99m-sestaMIBI scintigraphy.

BACKGROUND AND OBJECTIVE: The tracer tachnetium-99m-2-methoxy-isobutyl-isonitrile (Tc99m-sestaMIBI) has recently been shown to concentrate in some neoplastic tissues, including myeloma. We investigated the diagnostic capacity and limits of this procedure in tracing focal myeloma lesions, and compared them with those of conventional radiological procedures (Xr). DESIGN AND METHODS: We studied 55 patients suffering from multiple myeloma (MM) or solitary plasmacytoma in different stages and clinical conditions, or from monoclonal gammopathy of undefined significance (MGUS), by whole body scans obtained 10 minutes after injection of 555 MBq of Tc99m-sestaMIBI. Scans were defined as normal (physiological uptake only), diffuse (presence of bone marrow uptake), or focal (localized areas of uptake), and were compared to conventional skeletal Xr. RESULTS: Thirty patients showed no focal areas of Tc99m-sestaMIBI uptake; this group consisted of 5 patients with MGUS, 6 with MM in stage IA and 2 in stage IIA, 11 patients studied after effective chemotherapy and 6 in early relapse. Twenty-five patients showed one or more spots of focal uptake: all of them had active disease (untreated, resistant or relapsing MM). In the setting of tracing focal lesions, Tc99m-sestaMIBI scans were concordant with the radiological examination in 38 patients and discordant in 17. Among the latter, in 4 cases Tc99m-sestaMIBI revealed focal lesions not detected by Xr, and in 13 cases lytic areas detected by Xr did not show Tc99m-sestaMIBI uptake. INTERPRETATION AND CONCLUSIONS: In untreated patients, the number of lesions revealed by Tc99m-sestaMIBI was comparable to that shown by Xr, while in pretreated patients Tc99m-sestaMIBI traced a number of lesions lower than that detected by Xr. The reason for this discrepancy is that Tc99m-sestaMIBI traces only active lesions. Tc99m-sestaMIBI limitations in identifying focal lesions may derive from the dimension of the smallest traceable lesion (about one centimeter), and from the possibility that focal plasma cell localizations in collapsed bone may not be visualized due to inadequate vascularization. Tc99m-sestaMIBI scintigraphy is an interesting tool for diagnosing, staging and following up focal myeloma lesions, in the bone as well as in soft tissues. It is more specific than conventional Xr in identifying sites of active disease.

Carbonic anhydrase I reduction in colonic mucosa of patients with active ulcerative colitis.

Ulcerative colitis (UC) is associated with low intracolonic pH and unbalanced transmucosal ionic exchanges. Along the gastrointestinal tract carbonic anhydrase isoenzyme I (CA-I) is specifically expressed in colon epithelium and is involved in mucosal control of ion, fluid, and acid-base balance. Since altered CA-I expression may play some role in UC, CA-I was measured at the mRNA and protein level and carbonic anhydrase (CA) enzyme activity was determined in colon biopsies of 14 UC patients (6 remission, 4 mild, 4 moderate UC) and of 12 healthy subjects. Patients with mild or moderate UC showed a significant reduction of CA-I mRNA and protein and of total CA activity in the inflamed mucosa compared to controls. Patients with UC in remission showed a pattern of CA-I expression and CA activity similar to controls. This is the first report showing a reduction in the expression of CA-I in active UC.

Measurement of P-glycoprotein expression in multidrug-resistant human neuroblastoma cell lines using self-competitive binding assay.

To date, all reported measurements of multidrug resistance have been semiquantitative. The purpose of the present study is to establish and validate the self-competitive binding assay technique utilizing monoclonal antibody for quantitative estimation of multidrug resistance in tumor cells. This technique is used for P-glycoprotein concentration measurement in BE(2)-C human neuroblastoma cell line and its sublines with primary resistance to colchicine and actinomycin D. Monoclonal antibody MRK-16 was used in this study. It was labeled with iodine-125 (125I) to trace the concentration of antibody-antigen complexes. The binding data were obtained by varying the concentration of the unlabeled antibody. The results were fitted to a model equation to estimate the number of binding sites and antibody-antigen dissociation constant. The P-glycoprotein concentration was significantly higher in the resistant sublines than in the sensitive line. The highest levels were achieved in actinomycin D-resistant cells: 2.1 x 10(6) binding sites/cell versus 5.4 x 10(4) binding sites/cell in the sensitive cells. The consistency of the results was verified by repeating the study three times for each cell line. The binding assay results were confirmed by Western blot experiments performed on the same cell lines.

Local concentration of folate binding protein GP38 in sections of human ovarian carcinoma by in vitro quantitative autoradiography.

UNLABELLED: Folate binding protein (FBP) GP38 is a membrane-associated glycoprotein that mediates the intracellular transport of folates. The enhanced expression of FBP in ovarian carcinomas provided a rational basis for clinical studies with specific monoclonal antibodies and some newly synthesized antifolate drugs. Because the outcome of these clinical studies ultimately depends on the degree of FBP expression, we measured the local concentration of FBP using 125I-MOv18 monoclonal antibody and quantitative autoradiography. METHODS: Tissue sections from 37 specimens of ovarian carcinoma and 13 nonmalignant ovaries were incubated with increasing concentrations of 125I-MOv18 with and without an excess of unlabeled antibody. Tissue-bound radioactivity was measured by quantitative autoradiography. RESULTS: Folate binding protein was found to be overexpressed in 91% of nonmucinous ovarian carcinomas, with local concentrations ranging between 1.14 and 82.84 pmole/g. Adjacent tumor sections simultaneously studied with 125I-MOv18 and a 125I-labeled folic acid derivative showed matching and superimposable regional distributions of bound radioactivity of the two radioligands, indicating that the antigen, specifically recognized by 125I-MOv18 in nonmucinous ovarian carcinomas, is capable of binding folates. Nonmalignant ovaries did not contain measurable amounts of antigen when assayed with 125MOv18 but showed a limited and specific binding of the 125I-folic acid derivative to tissue sections. The autoradiographic findings were confirmed by testing sections from mixtures of antigen-positive and antigen-negative cells, by immunoperoxidase staining with MOv18 on tumor sections and by biochemical identification of FBP in membrane fractions from tissue samples. CONCLUSION: Folate binding protein is overexpressed up to 80-90-fold in nonmucinous ovarian carcinomas compared with nonmalignant ovaries. Quantitation of FBP may provide a useful tool in the design of clinical studies with specific monoclonal antibodies and certain antifolate drugs that enter the cell through FBP.

Characterization of the mucins produced by normal human colonocytes in primary culture.

Mature goblet cells filled with mucin ready for secretion represent about one third of the cells in primary cultures of human colonocytes. In the present study characterization of the mucins produced by cultured human colonocytes was made by histochemical methods by lectin and monoclonal antibody binding. Two monoclonal antibodies and three lectins (Dolichos biflorus (DBA), Helix pomatia (HPA) and Arachis hypogea (PNA) recognizing epitopes or sugar haptens characteristic of different stages of mucin glycoprotein maturation, were employed. The reactivity to these probes was tested both on cultured colonocytes and on tissue sections of the normal colon mucosa. The results show that the mucins produced in culture are glycosylated to the mature form, as they show the same reactivity to lectins and antibodies of the mucins expressed in tissue sections of the normal colon mucosa. In addition, it is demonstrated that cultured human colonocytes do not express mucins reactive to PNA, which are characteristic of tumors. Since the cultured colonocytes maintain the expression of differentiated functions for at least three days, they may offer a useful model to study metabolism, function and regulation of colon mucins in health and disease.

In vitro receptor imaging for characterization of human solid tumors.

Since many of the factors involved in tumor growth and progression act through a receptor-mediated mechanism, we applied in vitro receptor imaging techniques to study the intratumoral distribution and concentration of receptor-molecules having experimental biological relevance in such processes. Here we summarize the results of a study concerning the role of urokinase receptor (uPAR) in the acquisition of an invasive phenotype by tumor cells. Independently of the system studied, we demonstrated that in vitro receptor imaging techniques can be used to define the biological characteristics of human solid tumors and can contribute to clarify the complex network of ligand/receptor interactions leading to tumor spread.

Human colonocytes in primary culture: a model to study epithelial growth, metabolism and differentiation.

The purpose of this work was to set up an in vitro model for the study of normal and pathological functions of the colonic epithelium. We have isolated colonic crypts by mild proteolytic digestion and mechanical dissociation of human biopsy material obtained during colonoscopy. The crypts, free of connective tissue, when placed in culture rapidly attached to the substrate and formed colonies containing over 95% of epithelial cells. Histochemical and ultrastructural characterization of the colonies showed the presence of both absorptive and secretory cells, exhibiting a high degree of differentiation. Proliferative activity occurred mostly during the first 24 h and progressively declined thereafter. The cells survived and maintained differentiated characteristics for at least three days in culture. This method can be used to study normal functions of the colonic epithelium. It may also be employed to investigate both noxious and protective factors in pathological conditions such as inflammatory bowel disease and colorectal neoplasia.