Overcoming the Variability of iPSCs in the Manufacturing of Cell-Based Therapies

Various factors are known to contribute to the diversity of human induced pluripotent stem cells (hiPSCs). Among these are the donor's genetic background and family history, the somatic cell source, the iPSC reprogramming method, and the culture system of choice. Moreover, variability is seen even in iPSC clones, generated in a single reprogramming event, where the donor, somatic cell type, and reprogramming platform are the same. The diversity seen in iPSC lines often translates to epigenetic differences, as well as to differences in the expansion rate, iPSC line culture robustness, and their ability to differentiate into specific cell types. As such, the diversity of iPSCs presents a hurdle to standardizing iPSC-based cell therapy manufacturing. In this review, we will expand on the various factors that impact iPSC diversity and the strategies and tools that could be taken by the industry to overcome the differences amongst various iPSC lines, therefore enabling robust and reproducible iPSC-based cell therapy manufacturing processes.

Long-Term Stability and Differentiation Potential of Cryopreserved cGMP-Compliant Human Induced Pluripotent Stem Cells

The clinical effectiveness of human induced pluripotent stem cells (iPSCs) is highly dependent on a few key quality characteristics including the generation of high quality cell bank, long-term genomic stability, post-thaw viability, plating efficiency, retention of pluripotency, directed differentiation, purity, potency, and sterility. We have already reported the establishment of iPSC master cell banks (MCBs) and working cell banks (WCBs) under current good manufacturing procedure (cGMP)-compliant conditions. In this study, we assessed the cellular and genomic stability of the iPSC lines generated and cryopreserved five years ago under cGMP-compliant conditions. iPSC lines were thawed, characterized, and directly differentiated into cells from three germ layers including cardiomyocytes (CMs), neural stem cells (NSCs), and definitive endoderm (DE). The cells were also expanded in 2D and 3D spinner flasks to evaluate their long-term expansion potential in matrix-dependent and feeder-free culture environment. All three lines successfully thawed and attached to the L7^TM matrix, and formed typical iPSC colonies that expressed pluripotency markers over 15 passages. iPSCs maintained their differentiation potential as demonstrated with spontaneous and directed differentiation to the three germ layers and corresponding expression of specific markers, respectfully. Furthermore, post-thaw cells showed normal karyotype, negative mycoplasma, and sterility testing. These cells maintained both their 2D and 3D proliferation potential after five years of cryopreservation without acquiring karyotype abnormality, loss of pluripotency, and telomerase activity. These results illustrate the long-term stability of cGMP iPSC lines, which is an important step in establishing a reliable, long-term source of starting materials for clinical and commercial manufacturing of iPSC-derived cell therapy products.

Dynamic changes in replication timing and gene expression during lineage specification of human pluripotent stem cells

Duplication of the genome in mammalian cells occurs in a defined temporal order referred to as its replication-timing (RT) program. RT changes dynamically during development, regulated in units of 400-800 kb referred to as replication domains (RDs). Changes in RT are generally coordinated with transcriptional competence and changes in subnuclear position. We generated genome-wide RT profiles for 26 distinct human cell types, including embryonic stem cell (hESC)-derived, primary cells and established cell lines representing intermediate stages of endoderm, mesoderm, ectoderm, and neural crest (NC) development. We identified clusters of RDs that replicate at unique times in each stage (RT signatures) and confirmed global consolidation of the genome into larger synchronously replicating segments during differentiation. Surprisingly, transcriptome data revealed that the well-accepted correlation between early replication and transcriptional activity was restricted to RT-constitutive genes, whereas two-thirds of the genes that switched RT during differentiation were strongly expressed when late replicating in one or more cell types. Closer inspection revealed that transcription of this class of genes was frequently restricted to the lineage in which the RT switch occurred, but was induced prior to a late-to-early RT switch and/or down-regulated after an early-to-late RT switch. Analysis of transcriptional regulatory networks showed that this class of genes contains strong regulators of genes that were only expressed when early replicating. These results provide intriguing new insight into the complex relationship between transcription and RT regulation during human development.

Signaling network crosstalk in human pluripotent cells: a Smad2/3-regulated switch that controls the balance between self-renewal and differentiation

A general mechanism for how intracellular signaling pathways in human pluripotent cells are coordinated and how they maintain self-renewal remain to be elucidated. In this report, we describe a signaling mechanism where PI3K/Akt activity maintains self-renewal by restraining prodifferentiation signaling through suppression of the Raf/Mek/Erk and canonical Wnt signaling pathways. When active, PI3K/Akt establishes conditions where Activin A/Smad2,3 performs a pro-self-renewal function by activating target genes, including Nanog. When PI3K/Akt signaling is low, Wnt effectors are activated and function in conjunction with Smad2,3 to promote differentiation. The switch in Smad2,3 activity after inactivation of PI3K/Akt requires the activation of canonical Wnt signaling by Erk, which targets Gsk3β. In sum, we define a signaling framework that converges on Smad2,3 and determines its ability to regulate the balance between alternative cell states. This signaling paradigm has far-reaching implications for cell fate decisions during early embryonic development.

Epigenetic changes within the promoter region of the HLA-G gene in ovarian tumors

Background

Previous findings have suggested that epigenetic-mediated HLA-G expression in tumor cells may be associated with resistance to host immunosurveillance. To explore the potential role of DNA methylation on HLA-G expression in ovarian cancer, we correlated differences in HLA-G expression with methylation changes within the HLA-G regulatory region in an ovarian cancer cell line treated with 5-aza-deoxycytidine (5-aza-dC) and in malignant and benign ovarian tumor samples and ovarian surface epithelial cells (OSE) isolated from patients with normal ovaries.

Results

A region containing an intact hypoxia response element (HRE) remained completely methylated in the cell line after treatment with 5-aza-dC and was completely methylated in all of the ovarian tumor (malignant and benign) samples examined, but only variably methylated in normal OSE samples. HLA-G expression was significantly increased in the 5-aza-dC treated cell line but no significant difference was detected between the tumor and OSE samples examined.

Conclusion

Since HRE is the binding site of a known repressor of HLA-G expression (HIF-1), we hypothesize that methylation of the region surrounding the HRE may help maintain the potential for expression of HLA-G in ovarian tumors. The fact that no correlation exists between methylation and HLA-G gene expression between ovarian tumor samples and OSE, suggests that changes in methylation may be necessary but not sufficient for HLA-G expression in ovarian cancer.

Identification of candidate methylation-responsive genes in ovarian cancer

Background

Aberrant methylation of gene promoter regions has been linked to changes in gene expression in cancer development and progression. Genes associated with CpG islands (CGIs) are especially prone to methylation, but not all CGI-associated genes display changes in methylation patterns in cancers.

Results

In order to identify genes subject to regulation by methylation, we conducted gene expression profile analyses of an ovarian cancer cell line (OVCAR-3) before and after treatment with the demethylating agent 5-aza-deoxycytidine (5-aza-dC). An overlapping subset of these genes was found to display significant differences in gene expression between normal ovarian surface epithelial cells and malignant cells isolated from ovarian carcinomas. While 40% of all human genes are associated with CGIs, > 94% of the overlapping subset of genes is associated with CGIs. The predicted change in methylation status of genes randomly selected from the overlapping subset was experimentally verified.

Conclusion

We conclude that correlating genes that are upregulated in response to 5-aza-dC treatment of cancer cell lines with genes that are down-regulated in cancer cells may be a useful method to identify genes experiencing epigenetic-mediated changes in expression over cancer development.

L1 and HERV-W retrotransposons are hypomethylated in human ovarian carcinomas

Wide-spread hypomethylation of CpG dinucleotides is characteristic of many cancers. Retrotransposons have been identified as potential targets of hypomethylation during cellular transformation. We report the results of an preliminary examination of the methylation status of CpG dinucleotides associated with the L1 and HERV-W retrotransposons in benign and malignant human ovarian tumors. We find a reduction in the methylation of CpG dinucleotides within the promoter regions of these retroelements in malignant relative to non-malignant ovarian tissues. Consistent with these results, we find that relative L1 and HERV-W expression levels are elevated in representative samples of malignant vs. non-malignant ovarian tissues.

MRI evaluation of post-operative seromas in extremity soft tissue sarcomas

OBJECTIVE

To define the spectrum of MRI appearances of postoperative seromas in patients who have undergone excision of extremity soft tissue sarcomas. Local recurrence is always of concern; often a second-look procedure is performed to assess this possibility. Unnecessary surgical exploration may be avoided if radiologists and orthopedic oncologists are familiar with this spectrum of MRI appearances.

DESIGN AND PATIENTS

The medical records and images of 85 patients with extremity soft tissue sarcomas were reviewed. Postoperative MRI examinations were available in 46 patients. Eight of these demonstrated MRI evidence of postoperative seroma. The initial size, rate of change, margin, and internal architecture of each seroma was measured, calculated, graded, and graphed.

RESULTS AND CONCLUSION

MRI is an excellent modality for the evaluation of postoperative seromas. Globular areas of low to intermediate signal material within seromas may represent organized hematomas or granulation tissue rather than sarcoma recurrence. Local recurrence rarely occurs within seromas.

Changes in the responsiveness of parabrachial neurons in the arthritic rat: an electrophysiological study

1. Rats rendered polyarthritic by injection of Mycobacterium butyricum into the tail were used as a model for the study of "chronic pain". In such rats, anesthetized with halothane in a nitrous oxide-oxygen mixture, spontaneous activity and responses of parabrachial (PB) neurons to somatic stimulations were studied in comparison with those in a control group of healthy animals processed under the same experimental conditions. 2. The size of the somatic receptive field of PB neurons was similar in both arthritic and control groups. In the control group 13%, 55%, and 32% of the receptive fields were small, medium, and large, respectively. Similarly, in the arthritic group, 10%, 60%, and 30% of the receptive fields were small, medium, and large, respectively. 3. The spontaneous activity was significantly (P < 0.001) increased in the arthritic rats (0.1 < 3 < 16 Hz, n = 31; 10th percentile < median < 90th percentile) in comparison with the healthy rats (0.03 < 0.3 < 5 Hz, n = 22). 4. The sensitivity to mechanical stimuli was markedly increased in arthritic compared with healthy rats: 1) although PB neurons in normal rats never responded to innocuous stimuli, several PB neurons in arthritic rats responded to touch and/or joint movement; 2) the mean mechanical threshold decreased from 15.8 N/cm2 in normal rats to 5.9 N/cm2 in arthritic rats; 3) the mean pressure evoking 50% of the maximum response decreased from 34 N/cm2 in normal rats to 21 N/cm2 in arthritic rats; and 4) the intensity of the maximum response increased from 15.7 Hz in normal rats to 26.3 Hz in arthritic rats. 5. The mechanical encoding properties were clearly modified in arthritic rats compared with healthy rats. In this latter group, the PB neurons exhibited a clear capacity to encode mechanical stimuli in the noxious range: 1) the stimulus-response curves were always positive and monotonic until 48 N/cm2; and 2) the slope of the mean curve increased progressively from 2 to 8 N/cm2 before reaching a roughly linear maximum for a wide range of pressure (8-64 N/cm2) and plateauing beyond. In the arthritic rat, the PB neurons also encoded mechanical stimuli, but clearly from a lower pressure range: the slope of the mean curve was maximum and remained steep from the lowest pressure tested (1 N/cm2) up to 16 N/cm2; afterward the slope decreased progressively from 16 to 64 N/cm2 before plateauing. 6. The sensitivity to heat stimuli was only weakly modified. The thermal threshold was weakly, but significantly, increased from 44 degrees C in the normal rat to 45.8 degrees C in the arthritic rat. Other parameters for thermal modality were not changed, with the mean stimulus-response curves being similar in both arthritic and normal groups. 7. In conclusion, these experiments demonstrate that the activity of PB neurons is clearly changed in arthritic rats. These changes are reminiscent of some behavioral and electrophysiological modifications observed during arthritis. Considering the current literature, it is hypothesized that the PB relay could be responsible, at least in part, for several affective-emotional, behavioral, autonomic, and energy metabolism changes observed in arthritic rats.

Calmodulin inhibitors induce spinal analgesia in rats

Calcium is an important intracellular messenger that interacts with Ca(2+)-binding proteins, such as calmodulin (CaM), to activate several intracellular enzymes. The involvement of Ca2+ in the transmission of nociceptive signals has been demonstrated at the spina level. Specifically, spinal sensitization induced by persistent nociceptive stimulation seems to be related to an increase of cytosolic calcium and the subsequent activation of several enzymes, some of which are Ca2+/CaM dependent. In order to elucidate the possible implication of calmodulin in these pain processes, we have studied the effect of two calmodulin inhibitors (W-7 and calmidazolium) or the formalin and tail-flick tests in rats after their intrathecal administration. Antinociceptive effects were observed in both tests by injecting 0.12-1 mumol/rat of calmidazolium and 0.25-2 mumol/rat of W-7. Calmidazolium was more potent than W-7 in inhibiting both phases of the formalin test, whereas lower doses of W-7 in comparison to calmidazolium affected the tail-flick latencies. In addition, both drugs induced, at high doses, a muscular flaccidity of the hindlimbs that impaired normal walking in the rats. This effect caused; significant reduction of the rotarod performance when 1 mumol/rat of calmidazolium or 2 mumol/rat of W-7 were injected. Overall, our results show that calmodulin inhibitors are capable of producing spinal analgesia on phasic and tonic noxious stimuli in rats, thus rendering them a promising potential as analgesics.

Interaction among alfaxalone, pregnenolone sulfate, and two GABAA agonists on hippocampal slices

GABAA agonists do not respond to the same degree to allosteric modulators of the GABAA receptor complex such as benzodiazepines. We report there the effects of two steroids (alfaxalone and pregnenolone sulfate) on the inhibition induced by two GABAA agonists, 3-amino propane sulphonic acid (3-APS) and muscimol, on the extracellular evoked potentials obtained in CA1 of mice hippocampi. Alfaxalone (1 microM) potentiates the effects of both agonists, although incubation times longer than 15 minutes are required to potentiate the inhibitory effect of muscimol. Lower doses of pregnenolone sulfate at shorter incubation periods are able to inhibit the effects produced by single doses of 3-APS as compared to muscimol (15 microM during 5 min vs 30 microM during 5 min). Our results confirm the possibility that there might be differences in the interaction between GABAA agonists and modulatory steroids.

Parabrachial area: electrophysiological evidence for an involvement in cold nociception

1. Thirty-five percent of 120 neurons recorded extracellularly in the parabrachial (PB) area of anesthetized rats responded to a peripheral cold stimulus (0 degrees C). The cold-sensitive neurons were located in the lateral PB area, and most of those exhibiting a strong response to cold stimuli were inside or in close vicinity to the area receiving a high density of projections from superficial neurons of the dorsal horn. 2. The receptive fields for cold stimulation often were restricted to one or two parts of the body with a contralateral predominance for the limbs. No side predominance was observed for the face. 3. From a low spontaneous activity (10th percentile < median < 90th percentile: 0.1 < 1.5 < 5 Hz), the PB neurons responded to cold noxious stimuli (0 degree C water bath or waterjet, 20 s), without observable delay, with a sustained discharge. The mean maximal response to the stimulus was 16.1 +/- 1.2 Hz (mean +/- SE; n = 42). 4. About one-half (45%) of these cold-sensitive neurons were activated specifically by cold stimulation and did not respond or were inhibited by noxious heat and/or pinch. The remaining (55%) cold-sensitive neurons were also driven by heat and/or pinch. 5. The cold-sensitive neurons exhibited a clear capacity to encode cold stimuli in the noxious range: the stimulus-response function was always positive and monotonic from 30 to 0 degrees C; the mean curve was linear between 20 and 0 degrees C before plateauing between 0 to -10 degrees C; the mean threshold to cold stimulation was 17.1 +/- 1 degrees C (n = 21) and the mean t50 was 10.7 +/- 1.1 degrees C (n = 13). 6. The cold-sensitive neurons responded to intense transcutaneous electrical stimulation with an early and/or a late peak of activation, the latencies of which were in the 15-50 ms and 80-170 ms ranges (n = 8), respectively, i.e., compatible with the activation of A delta and C fibers. Interestingly, the cold-specific neurons predominantly responded with a late peak, suggesting these neurons were primarily driven by peripheral C fibers. 7. The intravenous injection of morphine depressed the responses of PB neurons to cold noxious stimuli in a dose-related (1, 3, and 9 mg/kg) and naloxone reversible fashion. The ED50 value was estimated approximately 2 mg/kg. Furthermore, two populations of neurons could be separated according to their morphine sensitivity. 8. It is concluded that PB cold-nonspecific neurons could be involved in affective-emotional, autonomic and neuroendocrine reactions in response to noxious cold events. The PB cold-specific neurons could be, in addition, involved in some thermoregulatory processes.

Spino (trigemino) parabrachiohypothalamic pathway: electrophysiological evidence for an involvement in pain processes

1. Parabrachiohypothalamic (PB-H) neurons (n = 71) were recorded with extracellular micropipettes in the parabrachial (PB) area and were antidromically driven from the ventromedial nucleus (VMH) or the retrochiasmatic area (RCh) of the hypothalamus, in the anesthetized rat. The spontaneous activity of these neurons was very low, (10th percentile < median frequency < 90th percentile were 0.01 < 0.2 < 7 Hz). The axons of these neurons exhibited a very slow conduction velocity in the range of 0.2-1.4 m/s, i.e., corresponding to thin unmyelinated fibers. 2. Most PB-H neurons (89%) were located in the mesencephalic division of the PB area (mPB) mainly in the superior lateral (mPBsl) and external lateral (mPBel) subnuclei. 3. These units were separated in three groups: 1) a group of nociceptive-specific (NS) neurons (49%) activated by mechanical and/or thermal (heat) cutaneous stimuli only in noxious range; 2) a group of inhibited neurons (7%), not activated by any of the mechanical or thermal cutaneous stimuli but inhibited, by at least one of these stimuli, which had to be in noxious range; and 3) a group of nonresponsive neurons (44%). 4. The NS neurons responded exclusively to mechanical (pinch or squeeze) and/or thermal (waterbath or waterjet > 44 degrees C) noxious stimuli with a rapid onset, a marked and sustained activation, and generally no afterdischarge. The magnitude of the responses was between 2 and 30 Hz with a mean value of 14.8 +/- 1.4 Hz (mean +/- SE, n = 49). These neurons exhibited a clear capacity to encode thermal stimuli in the noxious range: 1) the stimulus-response function was always positive and monotonic; 2) the slope of the mean curve increased up to a maximum (between 46 and 50 degrees C) then beyond the slope decreased; and 3) the mean threshold was 44.3 +/- 2.2 degrees C. 5. The excitatory receptive fields of the NS neurons were often large including all (22% of the population) or several (67% of the population) parts of the body. In the few remaining cases (11%) they were restricted to one part of the body. In addition, in several cases, noxious stimuli applied outside the excitatory receptive field were found to strongly inhibit the discharge of NS neurons. 6. Most NS neurons responded to intense transcutaneous electrical stimulation with two peaks of activation.(ABSTRACT TRUNCATED AT 400 WORDS)

Gender and test dependence of a type of kappa mediated stress induced analgesia in mice

1. In male mice, 80 inescapable footshocks (S-80) induce analgesic responses measured by the tail flick test that are blocked by naloxone and the kappa opioid antagonist, nor-binaltorphimine. We now study the nociceptive responses, induced after this particular stress, measured by the writhing test, the tail immersion test and a high intensity tail immersion test both in male and female mice. 2. In stressed males, analgesic responses are seen in all the nociceptive tests. Naloxone (10 mg/kg) does not prevent them. 3. In stressed females, in contrast with males, no analgesia is produced in the tail flick test. The writhing test and the tail immersion test registered analgesic responses that were not prevented by naloxone (10 mg/kg). 4. We conclude that only the antinociceptive kappa opioid mediated component of the stress we study is strongly dependent on gender, in contrast to other types of analgesia triggered by the same stress.

Serial thallium-201 scintigraphy in osteosarcoma. Correlation with tumor necrosis after preoperative chemotherapy

In 27 patients with extremity lesions (24 osteosarcoma, three malignant fibrous histiocytoma), a notable decrease in thallium-201 uptake was correlated with a good response to preoperative chemotherapy of the primary tumor. A good response is indicated by a greater than 95% tumor necrosis. Serial quantitative thallium-201 uptake of malignant bone tumors in patients receiving preoperative chemotherapy therefore can accurately predict a good histologic response and prognosis. Serial thallium scintigraphy can furthermore identify poor responses within two weeks after the initiation of treatment, or can prompt an early change in preoperative chemotherapy and facilitate limb salvage surgery.

Opioid footshock-induced analgesia in mice acutely falls by stress prolongation

The application of 80 footshocks (S-80) to mice induces a decrease in nociceptive responses as measured by the tail-flick test, which is opioid mediated as well as prevented by naloxone (10 mg/kg, SC). When the stress is prolonged up to 240 shocks (S-240) (i.e., from 6 min 40 s to 20 min), no analgesia can be seen immediately after the stress. We have examined the two most obvious possibilities, but they do not seem to be responsible for this fact. When morphine (1-5 mg/kg IP) is injected in the S-240 situation, a potentiation of its analgesic effects is seen, so that a desensitization of mu opioid receptors is unlikely. On the other hand, although cortisol (3-30 mg/kg IP) inhibits the analgesic response to S-80, metyrapone (40 and 80 mg/kg IP) and cortexolone (3-18 mg/kg IP) do not cause S-240 to be analgesic. Thus, an increase of endogenous glucocorticoids released during the long-duration stress does not seem responsible for the lack of analgesia after S-240.

Involvement of spinal kappa opioid receptors in a type of footshock induced analgesia in mice

We have studied the effects of several opioid antagonists on a type of footshock stress-induced analgesia (FSIA) measured by the tail-flick test in male mice. Naloxone injected either subcutaneously (0.1-10 mg/kg) or intrathecally (1-20 micrograms) antagonized FSIA at higher doses than those that blocked a similar degree of analgesia induced by morphine. Intracerebroventricular (i.c.v.) naloxone (1-20 micrograms) did not modify the FSIA while antagonizing the i.c.v. morphine-induced analgesia. As a consequence, the antagonism of the FSIA by naloxone probably occurs at the level of the spinal cord and through receptors different than mu. The delta selective antagonist naltrindole (0.1-3 mg/kg s.c.) did not antagonize the analgesic effects of the stress. Nor-binaltorphimine, a kappa selective antagonist, blocked the FSIA when administered systemically (1-4 mg/kg i.p.) or locally (0.1-1 microgram i.t.). These results strongly suggest that spinal kappa opioid receptors are responsible for this type of endogenous analgesia.

Limb salvage surgery for bone and soft tissue sarcoma. A phase II pathologic study of preoperative intraarterial cisplatin

Preoperative therapy has been tested as part of limb salvage therapy for localized bone and soft tissue sarcoma of the extremities. The activity of cisplatin (CDDP) by intraarterial (IA) infusion was evaluated in 40 cases of which 36 were evaluable for response. All patients had high-grade sarcomas. All but 3 patients received 3 or 4 courses (24 patients received 4 courses) of CDDP at a dosage of 120 to 150 mg/m2 given over 6 hours every 2 weeks by IA infusion. Patients younger than 18 years of age received the higher dose of CDDP. Treatment was well tolerated with combination antiemetics. One patient experienced severe hearing loss with the first cycle of the higher CDDP dose. Pathologic evaluation of resected osteosarcoma showed a favorable response (90% or greater necrosis) in 8 of 20 evaluable cases and in 3 of 4 patients with malignant fibrous histiocytoma (MFH) of bone (without osteoid). In soft tissue sarcomas, minimal (50% to 89%) necrosis was seen in two of nine cases and none had 90% or greater necrosis. Patients received postoperative chemotherapy based on pathologic response, but the value of this postoperative adjuvant therapy requires further follow-up and is uncertain in this small study. IA CDDP can often cause significant tumor necrosis in patients with bone sarcomas, whereas soft tissue sarcomas are less sensitive to this therapy.

Limited posterolateral surgical approach to the knee for excision of osteoid osteoma

An 18-year-old man suffered four years of undiagnosed knee pain until a CAT scan revealed an epiphyseal osteoid osteoma of the tibia located subchondrally, just medial to the proximal tibiofibular joint. A nidus in this location is not easily accessible, and its proximity to the joint surface raised concerns about damage to the tibial plateau. To facilitate excision of the tumor, cadaveric dissections were performed to develop a limited posterior approach to the proximal, lateral portion of the tibia. The CAT scan was used to calculate the precise dimensions of the tumor and its relation to the posterior tibial cortex and the proximal tibiofibular joint. With the use of the exposure developed in the laboratory and the calculations derived from the CAT scan, the tumor could be excised by removing a single block of bone 15 mm3. Intraoperative radiographs confirmed the presence of the nidus within the excised block of bone. This case report reaffirms the frequent difficulties and tardiness in diagnosing osteoid osteomas and the need to include these tumors in the differential diagnosis of knee pain and epiphyseal lesions. Before CAT scans were used, the working diagnoses were torn meniscus, juvenile rheumatoid arthritis, and bone hemangiomatosis.

Efficacy of mycophenolic acid for the treatment of psoriasis

The efficacy of orally administered mycophenolic acid (MPA), an inhibitor of guanosine monophosphate (GMP) synthesis, for the treatment of psoriasis, was studied in a double-blind fashion. Of twenty-one patients completing the study period, ten of eleven patients treated with MPA had a greater than 25% decrease in severity score compared with only two of ten patients treated with placebo. The placebo group had a slight increase in severity score compared to almost 50% reduction in the average severity score of the MPA-treated group. After termination of the double-blind portion of the study, the placebo group was treated with MPA and showed a 60% decrease in severity score. Adverse effects encountered included anorexia, nausea, vomiting, and diarrhea. One patient had an uncomplicated episode of herpes zoster. Other than a mild decrease hemoglobin, no hematologic toxicity was noted.

Treatment of psoriasis with oral mycophenolic acid

Mycophenolic acid (MPA), an inhibitor of purine synthesis, was evaluated for its therapeutic and adverse effects in 29 patients with psoriasis. MPA was administered orally for at least 12 weeks, during which time the daily dose was increased from 1600 to 4800 mg depending on occurrence of adverse reactions. Complete clearing occurred in 1 of the patients, almost complete clearing in 14, definite improvement in 13, slight or doubtful improvement in 1. The full effect of MPA required a median time of 8 weeks (range 5-14). After discontinuing MPA, relapses began at a median time of 4 weeks (range 3-8). The severity of psoriasis was scored on a 0 to 108 scale using a newly devised system. The mean severity and range before treatment was 47 (21-88); after 12 weeks, 15 (0-50). Adjustment of dose on the basis of side effects resulted in a median daily dose of 3600 mg (range 2400-4800 mg; 30-96 mg/kg ideal weight). Characteristic dose-limiting side effects were soft or frequent bowel movements, diarrhea, nausea, and anorexia. One instance of reversible, dose-related leukopenia was identified.