Evaluation of two (125)I-radiolabeled acridine derivatives for Auger-electron radionuclide therapy of melanoma.

We previously selected two melanin-targeting radioligands [(125)I]ICF01035 and [(125)I]ICF01040 for melanoma-targeted (125)I radionuclide therapy according to their pharmacological profile in mice bearing B16F0 tumors. Here we demonstrate in vitro that these compounds present different radiotoxicities in relation to melanin and acidic vesicle contents in B16F0, B16F0 PTU and A375 cell lines. ICF01035 is effectively observed in nuclei of achromic (A375) melanoma or in melanosomes of melanized melanoma (B16F0), while ICF01040 stays in cytoplasmic vesicles in both cells. [(125)I]ICF01035 induced a similar survival fraction (A50) in all cell lines and led to a significant decrease in S-phase cells in amelanotic cell lines. [(125)I]ICF01040 induced a higher A50 in B16 cell lines compared to [(125)I]ICF01035 ones. [(125)I]ICF01040 induced a G2/M blockade in both A375 and B16F0 PTU, associated with its presence in cytoplasmic acidic vesicles. These results suggest that the radiotoxicity of [(125)I]ICF01035 and [(125)I]ICF01040 are not exclusively reliant on DNA alterations compatible with γ rays but likely result from local dose deposition (Auger electrons) leading to toxic compound leaks from acidic vesicles. In vivo, [(125)I]ICF01035 significantly reduced the number of B16F0 lung colonies, enabling a significant increase in survival of the treated mice. Targeting melanosomes or acidic vesicles is thus an option for future melanoma therapy.

In vivo efficacy of melanoma internal radionuclide therapy with a 131I-labelled melanin-targeting heteroarylcarboxamide molecule.

The development of alternative therapies for melanoma treatment is of great interest as long-term tumour regression is not achieved with new targeted chemotherapies on selected patients. We previously demonstrated that radioiodinated heteroarylcarboxamide ([131I]ICF01012) induced a strong anti-tumoural effect by inhibiting both primary tumour growth and dissemination process in a B16BL6 melanoma model. In our study, we show that a single injection of [131I]ICF01012 (ranging from 14.8 to 22.2 MBq) was effective and associated with low and transient haematological toxicity. Concerning pigmented organs, cutaneous melanocytes and skin were undamaged. In 30% of treated animals, no histological alteration of retina was observed, and in the remaining 70%, damages were restricted to the optic nerve area. Using the Medical Internal Radiation Dose methodology, we determined that the absorbed dose in major organs is very low (<4 Gy) and that a delivery of 30 Gy to the tumour is sufficient for an effective anti-tumoural response. Molecular analyses of treated tumours showed a strong radiobiological effect with a decrease in proliferation, survival and pro-angiogenic-related markers and an increase in tumour suppressor gene expression, melanogenesis and anti-angiogenic markers. All these features are in accordance with a tumour cell death mechanism that mainly occurs by mitotic catastrophe and provide a better understanding of in vivo anti-tumoural effects of [131I] radionuclide. Our findings raise [131I]ICF01012 a good candidate for disseminated melanoma treatment and strongly support transfer of [131I]ICF01012 to clinical trial.

Evaluation of new iodinated acridine derivatives for targeted radionuclide therapy of melanoma using 125I, an Auger electron emitter.

The increasing incidence of melanoma and the lack of effective therapy on the disseminated form have led to an urgent need for new specific therapies. Several iodobenzamides or analogs are known to possess specific affinity for melanoma tissue. New heteroaromatic derivatives have been designed with a cytotoxic moiety and termed DNA intercalating agents. These compounds could be applied in targeted radionuclide therapy using (125)I, which emits Auger electrons and gives high-energy, localized irradiation. Two iodinated acridine derivatives have been reported to present an in vivo kinetic profile conducive to application in targeted radionuclide therapy. The aim of the present study was to perform a preclinical evaluation of these compounds. The DNA intercalating property was confirmed for both compounds. After radiolabeling with (125)I, the two compounds induced in vitro a significant radiotoxicity to B16F0 melanoma cells. Nevertheless, the acridine compound appeared more radiotoxic than the acridone compound. While cellular uptake was similar for both compounds, SIMS analysis and in vitro protocol showed a stronger affinity for melanin with acridone derivative, which was able to induce a predominant scavenging process in the melanosome and restrict access to the nucleus. In conclusion, the acridine derivative with a higher nuclear localization appeared a better candidate for application in targeted radionuclide therapy using (125)I.

Proteomic studies of B16 lines: involvement of annexin A1 in melanoma dissemination.

To identify proteins involved in melanoma metastasis mechanisms, comparative proteomic studies were undertaken on B16F10 and B16Bl6 melanoma cell lines and their subsequent syngenic primary tumours as pulmonary metastases were present only in the mice bearing a B16Bl6 tumour. 2DE analyses followed by MALDI-TOF identification showed variations of 6 proteins in vitro and 13 proteins in vivo. Differential expressed proteins in tumours were related to energy production and storage. Two differentially expressed proteins which had not been previously associated to melanoma progression, annexin A1 (ANXA1) and creatine kinase B (CKB), were found both in cells and in tumours. To characterize ANXA1 involvement in melanoma B16 dissemination, we reduced ANXA1 protein level by siRNA and observed a significant decrease of B16Bl6 cell invasion through Matrigel coated chambers. We further demonstrated that the presence of several formyl peptide receptors (FPR1, FPRrs1 and 2) revealed by qRT-PCR, played a role in B16 invasion: incubation of B16Bl6 cells with the FPR agonist (fMLP) or antagonist (tBOC) enhanced or decreased Matrigel coated chamber invasion respectively, with a correlation of ANXA1 levels in both treatments. As ANXA1 could bind to FPRs, this should amplify invasion and enhance melanoma dissemination.

Targeted radionuclide therapy of melanoma: anti-tumoural efficacy studies of a new 131I labelled potential agent.

In recent years, there has been dramatic worldwide increase in incidence of malignant melanoma. Although localised disease is often curable by surgical excision, metastatic melanoma is inherently resistant to most treatments. In this context, targeted radionuclide therapy could be an efficient alternative. After pharmacomodulation study, we selected a quinoxaline derivative molecule (ICF01012) for its high, specific and long-lasting uptake in melanoma with rapid clearance from nontarget organs providing suitable dosimetry parameters for targeted radiotherapy. Aim of this study was to investigate, in vivo, efficacy of [(131)I]ICF01012 on nonmetastatic B16F0, metastatic B16Bl6 or human M4Beu melanoma tumours. First, colocalisation of ICF01012 with melanin by SIMS imaging was observed. Second, we showed that treatment drastically inhibited growth of B16F0, B16Bl6 and M4beu tumours whereas [(131)I]NaI or unlabelled ICF01012 treatment was without significant effect. Histological analysis and measure of PCNA proliferation marker expression showed that residual B16 tumour cells exhibit a significant loss of aggressiveness after treatment. This effect is associated with a lengthening of the treated-mice survival time. Moreover, with B16Bl6 model, 55% of the untreated mice had lung metastases whereas no metastasis was counted on treated group. Our data demonstrated a strong anti-tumoural effect of [(131)I]ICF01012 for radionuclide therapy on murine and human in vivo pigmented melanoma models, whatever their dissemination profiles and their melanin content be. Further studies will attempt to optimise therapy protocol by increasing the balance between the anti-tumoural effect and the safety on non-target organs.

A new O6-alkylguanine-DNA alkyltransferase inhibitor associated with a nitrosourea (cystemustine) validates a strategy of melanoma-targeted therapy in murine B16 and human-resistant M4Beu melanoma xenograft models.

Chemoresistance to O(6)-alkylating agents is a major barrier to successful treatment of melanoma. It is mainly due to a DNA repair suicide protein, O(6)-alkylguanine-DNA alkyltransferase (AGT). Although AGT inactivation is a powerful clinical strategy for restoring tumor chemosensitivity, it was limited by increased toxicity to nontumoral cells resulting from a lack of tumor selectivity. Achieving enhanced chemosensitization via AGT inhibition preferably in the tumor should protect normal tissue. To this end, we have developed a strategy to target AGT inhibitors. In this study, we tested a new potential melanoma-directed AGT inhibitor [2-amino-6-(4-iodobenzyloxy)-9-[4-(diethylamino) ethylcarbamoylbenzyl] purine; IBgBZ] designed as a conjugate of O(6)-(4-iododbenzyl)guanine (IBg) as the AGT inactivator and a N,N-diethylaminoethylenebenzamido (BZ) moiety as the carrier to the malignant melanocytes. IBgBZ demonstrated AGT inactivation ability and potentiation of O(6)-alkylating agents (cystemustine, a chloroethylnitrosourea) in M4Beu highly chemoresistant human melanoma cells both in vitro and in tumor models. The biodisposition study on mice bearing B16 melanoma, the standard model for the evaluation of melanoma-directed agents, and the secondary ion mass spectrometry imaging confirmed the concentration of IBgBZ in the tumor and in particular in the intracytoplasmic melanosomes. These results validate the potential of IBgBZ as a new, more tumor-selective, AGT inhibitor in a strategy of melanoma-targeted therapy.

Synthesis, radiosynthesis, and biological evaluation of new proteasome inhibitors in a tumor targeting approach.

Proteasome inhibition is a new strategy in cancer therapy. We synthesized three new peptide aldehyde inhibitors linked to the benzamide derivative structure to use their cytotoxic activity against malignant melanoma cells. Of these, 10 displayed the highest cytotoxicity (0.18 +/- 0.16 microM). A radiosynthesis of the iodine aldehyde was performed. Its drug biodistribution showed that some selectivity of the benzamide group toward malignant melanoma tissue was conserved.

Evaluation of radiolabeled (hetero)aromatic analogues of N-(2-diethylaminoethyl)-4-iodobenzamide for imaging and targeted radionuclide therapy of melanoma.

Targeted radionuclide therapy using radioiodinated compounds with a specific affinity for melanoma tissue is a promising treatment for disseminated melanoma, but the candidate with the ideal kinetic profile remains to be discovered. Targeted radionuclide therapy concentrates the effects on tumor cells, thereby increasing the efficacy and decreasing the morbidity of radiotherapy. In this context, analogues of N-(2-diethylaminoethyl)-4-iodobenzamide (BZA) are of interest. Various (hetero)aromatic analogues 5 of BZA were synthesized and radioiodinated with (125)I, and their biodistribution in melanoma-bearing mice was studied after i.v. administration. Most [ (125)I] 5-labeled compounds appeared to bind specifically and with moderate-to-high affinity to melanoma tumor. Two compounds, 5h and 5k, stood out with high specific and long-lasting uptake in the tumor, with a 7- and 16-fold higher value than BZA at 72 h, respectively, and kinetic profiles that makes them promising agents for internal targeted radionuclide therapy of melanoma.

Melanoma affinity in mice and immunosuppressed sheep of [(125)I]N-(4-dipropylaminobutyl)-4-iodobenzamide, a new targeting agent.

The increasing incidence of melanoma and the lack of effective therapy have prompted the development of new vectors, more specific to the pigmented tumor, for early detection and treatment. Targeted agents have to exhibit a rapid, high tumor uptake, long tumor retention and rapid clearance from nontarget organs. This joint work presents results obtained with a new melanoma targeting agent, [(125)I]-N-(4-dipropylaminobutyl)-4-iodobenzamide or [(125)I]BZ18. After labeling with a high specific activity, the biodistribution of the compound was investigated in two animal models, the mouse and the sheep. Melanotic tumor retention was observed lasting several days. We visualized the internalization of the agent inside the melanosomes by secondary ion mass spectroscopy imaging, we measured the affinity constants of [(125)I]BZ18 on a synthetic melanin model and we demonstrated a radiotoxic effect of this labeled agent on B16F0 melanoma cell culture due to its cellular internalization. From this work, [(125)I]BZ18 appeared a promising melanoma targeting agent in the nuclear medicine field.

Design, synthesis and preliminary biological evaluation of acridine compounds as potential agents for a combined targeted chemo-radionuclide therapy approach to melanoma.

Various iodo-acridone and acridine carboxamides have been prepared and evaluated as agents for targeted radionuclide and/or chemotherapy for melanoma, due to their structural similarity to benzamides which are known to possess specific affinity for melanin. Three of these carboxamides selected for their in vitro cytotoxic properties were radioiodinated with [(125)I]NaI at high specific activity. Biodistribution studies carried out in B16F0 murine melanoma tumour-bearing mice highlighted that acridone 8f and acridine 9d, presented high, long-lasting tumour concentrations together with an in vivo kinetic profile favourable to application in targeted radionuclide therapy.

Development of a high-performance liquid chromatographic method for the determination of a new potent radioiodinated melanoma imaging and therapeutic agent.

N-(2-diethylaminoethyl)-6-iodoquinoxaline-2-carbamide (ICF 01012) is a new melanoma imaging agent showing promising properties for application in internal radionuclide therapy. We developed an analytical protocol for detection of ICF 01012 in biological samples using HPLC. The proposed method was first validated using standard of ICF 01012 and four potent metabolites of this compound and then applied to follow the metabolic fate of [(125)I]ICF 01012 after injection in melanoma-bearing mice. The results demonstrate that this method exhibits a good linearity (r(2)=0.9947), specificity and acceptable accuracy. This simple method appears convenient and sufficient for pharmacokinetic studies on [(125)I]ICF 01012.

Melanoma tumors acquire a new phospholipid metabolism phenotype under cystemustine as revealed by high-resolution magic angle spinning proton nuclear magnetic resonance spectroscopy of intact tumor samples.

N'-[2-chloroethyl]-N[2-(methylsulfonyl) ethyl]-N'-nitrosourea (cystemustine),a chloroethylnitrosourea antineoplastic drug, provokes cellular proliferation inhibition and redifferentiation, but there was no cell death in B16 melanoma tumors. Because the phospholipid (Plp) metabolism is tightly involved in tumor growth regulation and tumor cell survival, we tested the hypothesis that melanoma tumors undergo adaptive Plp metabolism changes to survive treatment. Measurements of Plp derivatives were performed using a novel proton nuclear magnetic resonance Spectroscopy application using magic angle spinning on intact tumor tissue samples. Phosphatidylcholine levels were obtained from one-dimensional spectra, and relative levels of choline- and ethanolamine-containing compounds were derived from two-dimensional spectra (total correlation spectroscopy sequence). Two major findings emerged from this study: (a) during tumor growth inhibition, there was a transient accumulation of choline, glycerophosphocholine, and glycerophosphoethanolamine and a sustained increase in phosphocholine and phosphoethanolamine, whereas phosphatidylcholine levels remained unchanged; and (b) during tumor growth recovery, only phosphocholine and phosphoethanolamine remained elevated. Therefore, cystemustine-treated B16 melanoma tumors acquire a new Plp metabolism phenotype, a mechanism that could participate in tumor cell redifferentiation and/or survival.

Secondary ion mass spectrometry as a tool for investigating radiopharmaceutical distribution at the cellular level: the example of I-BZA and (14)C-I-BZA.

UNLABELLED: Further development of nuclear medicine for imaging and internal radiotherapy demands a precise knowledge of the tissue and cellular distribution of radiopharmaceuticals. Ion microscopy (secondary ion mass spectrometry [SIMS]) may be particularly useful in this respect. We used SIMS to study the biodistribution of the melanoma-targeting molecule N-(2-diethylaminoethyl)-4-iodobenzamide (I-BZA), both in its native state and radiolabeled with (14)C. METHODS: C57BL6/J1/co mice bearing pulmonary colonies of B16 melanoma cells were injected with I-BZA or (14)C-I-BZA. Appropriate tissues were fixed and included in epoxy embedding resin for SIMS studies. The distribution of unlabeled I-BZA was studied by detecting its stable iodine atom ((127)I). (14)C-I-BZA distribution was studied by dual detection of (127)I and (14)C. The time course of I-BZA concentrations at sites of tissue fixation was studied by measuring the signal ratio of (14)C and the naturally occurring isotope (13)C. RESULTS: SIMS showed that I-BZA concentrated in the cytoplasm of tumoral melanocytes (melanoma cells) and in the cytoplasm of tumor-infiltrating macrophages (melanophages). I-BZA was also detected in the cytoplasm of normal melanocytes in the pigmented structures of skin and eye. Interpretation of I-BZA distribution by using electron micrographs of adjacent sections showed that the intracytoplasmic melanin-rich organelles (melanosomes) were responsible for I-BZA retention. The distributions of (127)I and (14)C after (14)C-I-BZA injection were identical, even when I-BZA was separately labeled with (14)C at 2 different positions, indicating the stability of the amide bond of I-BZA. The time course of the (14)C/(13)C ratio in the melanosomes of melanoma cells suggested a retention half-life of about 38 h. CONCLUSION: Contrary to previous suggestions that I-BZA fixes principally to sigma-1 membrane receptors, our results strongly indicate that I-BZA associates with intracytoplasmic melanin pigments. Early I-BZA accumulation, in both melanocytes and melanophages, suggests that this compound fixes to preformed melanin rather than being incorporated during de novo melanin synthesis. These quantitative and qualitative data obtained with I-BZA illustrate the excellent potential of SIMS for studying the biologic fate of radiopharmaceuticals.

Uptake in melanoma cells of N-(2-diethylaminoethyl)-2-iodobenzamide (BZA2), an imaging agent for melanoma staging: relation to pigmentation.

N-(2-diethylaminoethyl)-2-iodobenzamide (BZA(2)) has been singled out as the most efficacious melanoma scintigraphy imaging agent. Our work was designed to assess the mechanisms of the specific affinity of the radioiodinated iodobenzamide for melanoma tissue. We studied the cellular uptake and retention of [(125)I]-BZA(2) on various cell lines. In vitro, cellular [(125)I]-BZA(2) uptake was related to the pigmentation status of the cells: higher in pigmented melanoma cell lines (M4 Beu, IPC 227, B 16) than in a nonpigmented one (M3 Dau) and nonmelanoma cell lines (MCF 7 and L 929). Two mechanisms were assessed: binding of the tracer to melanin or to sigma receptors of melanoma cells. First, the uptake of [(125)I]-BZA(2) after melanogenesis stimulation by alpha-melanocyte-stimulating hormone and l-tyrosine increased in the B 16 melanoma cell line both in vitro and in vivo according to melanin concentration. Moreover, the binding of [(125)I]-BZA(2) to synthetic melanin was dependent on melanin concentration and could be saturated. Second, no competition was evidenced on M4 Beu cells between [(125)I]-BZA(2) and haloperidol, a sigma ligand, at concentrations < or =10(-6) M. We show that the specificity and sensibility of BZA(2) as a melanoma scintigraphic imaging agent are mostly due to interactions with melanic pigments.

Synthesis, in vitro binding and biodistribution in B16 melanoma-bearing mice of new iodine-125 spermidine benzamide derivatives.

In the course of our investigations aimed at improving the biological characteristics of iodobenzamides for melanoma therapeutic applications, four new derivatives containing a spermidine chain have been prepared and radiolabeled with (125)I. In vitro studies showed that all compounds displayed high affinity for melanin superior to the reference compound BZA, thus validating our experimental approach. In vivo biodistribution was investigated in B16 melanoma-bearing mice. All four compounds, particularly benzamide 3, showed accumulation in the tumor, but lower, however, than that of BZA. Moreover, high concentrations of radioactivity in other organs, namely, the liver and lung, demonstrated nonspecific tumoral uptake. In view of these results, compounds 1 2 3 4 do not appear to be suitable radiopharmaceuticals for melanoma radionuclide therapy.

Ultra-structural cell distribution of the melanoma marker iodobenzamide: improved potentiality of SIMS imaging in life sciences.

BACKGROUND: Analytical imaging by secondary ion mass spectrometry (SIMS) provides images representative of the distribution of a specific ion within a sample surface. For the last fifteen years, concerted collaborative research to design a new ion microprobe with high technical standards in both mass and lateral resolution as well as in sensitivity has led to the CAMECA NanoSims 50, recently introduced onto the market. This instrument has decisive capabilities, which allow biological applications of SIMS microscopy at a level previously inaccessible. Its potential is illustrated here by the demonstration of the specific affinity of a melanoma marker for melanin. This finding is of great importance for the diagnosis and/or treatment of malignant melanoma, a tumour whose worldwide incidence is continuously growing. METHODS: The characteristics of the instrument are briefly described and an example of application is given. This example deals with the intracellular localization of an iodo-benzamide used as a diagnostic tool for the scintigraphic detection of melanic cells (e.g. metastasis of malignant melanoma). B16 melanoma cells were injected intravenously to C57BL6/J1/co mice. Multiple B16 melanoma colonies developed in the lungs of treated animals within three weeks. Iodobenzamide was injected intravenously in tumour bearing mice six hours before sacrifice. Small pieces of lung were prepared for SIMS analysis. RESULTS: Mouse lung B16 melanoma colonies were observed with high lateral resolution. Cyanide ions gave "histological" images of the cell, representative of the distribution of C and N containing molecules (e.g. proteins, nucleic acids, melanin, etc.) while phosphorus ions are mainly produced by nucleic acids. Iodine was detected only in melanosomes, confirming the specific affinity of the drug for melanin. No drug was found in normal lung tissue. CONCLUSION: This study demonstrates the potential of SIMS microscopy, which allows the study of ultra structural distribution of a drug within a cell. On the basis of our observations, drug internalization via membrane sigma receptors can be excluded.

Annexin A1 in primary tumors promotes melanoma dissemination.

Metastatic melanoma is one of the most aggressive forms of skin cancer and has a poor prognosis. We have previously identified Annexin A1 (ANXA1) as a potential murine melanoma-spreading factor that may modulate cell invasion by binding to formyl peptide receptors (FPRs). Here, we report that (1) in a B16Bl6 spontaneous metastasis model, a siRNA-induced decrease in tumoral ANXA1 expression significantly reduced tumoral MMP2 activity and number of lung metastases; (2) in a retrospective study of 61 patients, metastasis-free survival was inversely related to ANXA1 expression levels in primary tumors (HR 3.15 [1.03-9.69], p = 0.045); (3) in human melanoma cell lines, ANXA1 level was positively correlated with in vitro invasion capacity whereas normal melanocytes contained low ANXA1 levels, and (4) the ANXA1 N-terminal peptide ANXA12-26 stimulated MMP2 activity after interaction with FPRs and significantly stimulated the in vitro invasion of melanomas by acting on FPRs. These findings identify ANXA1 as a proinvasive protein in melanoma that holds promise as a potential prognostic marker and therapeutic target.

Synthesis, radioiodination and in vivo screening of novel potent iodinated and fluorinated radiotracers as melanoma imaging and therapeutic probes.

In order to develop new iodinated and fluorinated matched-pair radiotracers for Single-Photon Emission Computed Tomography (SPECT)/Positron Emission Tomography (PET) imaging and targeted radionuclide therapy of melanoma, we successfully synthesized and radiolabelled with iodine-125 seven new derivatives, starting from our previously described lead structure 3. The relevance of these radiotracers for gamma scintigraphic imaging of melanoma in rodent was assessed. The tumoural radioactivity uptake was most often high and specific even at early time points (12.1-18.3% ID/g at 3 h p.i. for [(125)I]39-42) and a fast clearance from the non-target organs was observed. Also, calculated effective doses that could be delivered to tumours when using corresponding [(131)I]-labelled analogues were generally higher than 100 cGy/MBq injected (98.9-150.5 cGy/MBq for [(131)I]39-42). These results make compounds 39-42 suitable candidates for (i) PET imaging of melanoma after labelling with fluorine-18 and (ii) targeted radionuclide therapy of disseminated melanoma after labelling with iodine-131.

Single photon emission computed tomography/positron emission tomography imaging and targeted radionuclide therapy of melanoma: new multimodal fluorinated and iodinated radiotracers.

This study reports a series of 14 new iodinated and fluorinated compounds offering both early imaging ((123)I, (124)I, (18)F) and systemic treatment ((131)I) of melanoma potentialities. The biodistribution of each (125)I-labeled tracer was evaluated in a model of melanoma B16F0-bearing mice, using in vivo serial γ scintigraphic imaging. Among this series, [(125)I]56 emerged as the most promising compound in terms of specific tumoral uptake and in vivo kinetic profile. To validate our multimodality concept, the radiosynthesis of [(18)F]56 was then optimized and this radiotracer has been successfully investigated for in vivo PET imaging of melanoma in B16F0- and B16F10-bearing mouse model. The therapeutic efficacy of [(131)I]56 was then evaluated in mice bearing subcutaneous B16F0 melanoma, and a significant slow down in tumoral growth was demonstrated. These data support further development of 56 for PET imaging ((18)F, (124)I) and targeted radionuclide therapy ((131)I) of melanoma using a single chemical structure.

Longitudinal profiling of articular cartilage degradation in osteoarthritis by high-resolution magic angle spinning 1H NMR spectroscopy: experimental study in the meniscectomized guinea pig model.

This study assessed the 1H HRMAS NMR spectroscopic profile of articular cartilage in both physiological and osteoarthitic situations. One-dimensional and two-dimensional 1H HRMAS NMR spectra were obtained from the tibial plateau cartilage of healthy and operated (unilateral medial meniscectomy and sham surgery) guinea pigs at different stages of disease, over a 6-month period. The major osteoarthritis-induced 1H HRMAS NMR changes were an increase of the N-acetyl peak of proteoglycans (at day 20 after meniscectomy) and a decrease after day 60 as the pathology evolved. These proteoglycan changes revealed by 1H HRMAS NMR analysis were validated by proteoglycan biochemistry assays. 1H HRMAS NMR analysis also evidenced a sharp increase in methylene resonances of chondrocyte membrane lipids from day 90 as a marker of apoptosis. There was an increase of the mobile methyl group of collagen at day 120, which was associated with collagen breakdown. 1H HRMAS NMR analysis provided a multifactorial and sequential picture of cartilage degradation at the extracellular matrix and chondrocyte levels.