Purpose Circulating tumor cell (CTC) enumeration has not been prospectively validated in standard first-line docetaxel treatment for metastatic castration-resistant prostate cancer. We assessed the prognostic value of CTCs for overall survival (OS) and disease response in S0421, a phase III trial of docetaxel plus prednisone with or without atrasentan. Patients and Methods CTCs were enumerated at baseline (day 0) and before cycle two (day 21) using CellSearch. Baseline counts and changes in counts from day 0 to 21 were evaluated for association with OS, prostate-specific antigen (PSA), and RECIST response using Cox regression as well as receiver operator characteristic (ROC) curves, integrated discrimination improvement (IDI) analysis, and regression trees. Results Median day-0 CTC count was five cells per 7.5 mL, and CTCs < versus ≥ five per 7.5 mL were significantly associated with baseline PSA, bone pain, liver disease, hemoglobin, alkaline phosphatase, and subsequent PSA and RECIST response. Median OS was 26 months for < five versus 13 months for ≥ five CTCs per 7.5 mL at day 0 (hazard ratio [HR], 2.74 [adjusting for covariates]). ROC curves had higher areas under the curve for day-0 CTCs than for PSA, and IDI analysis showed that adding day-0 CTCs to baseline PSA and other covariates increased predictive accuracy for survival by 8% to 10%. Regression trees yielded new prognostic subgroups, and rising CTC count from day 0 to 21 was associated with shorter OS (HR, 2.55). Conclusion These data validate the prognostic utility of CTC enumeration in a large docetaxel-based prospective cohort. Baseline CTC counts were prognostic, and rising CTCs at 3 weeks heralded significantly worse OS, potentially serving as an early metric to help redirect and optimize therapy in this clinical setting.

Using an unbiased genetic screen in mice, Hartmut Geiger et al. found that the thrombomodulin–activated protein C pathway, which controls blood coagulation among other functions, also protects from radiation damage. Administration of a recombinant variant of thrombomodulin or of recombinant activated protein C protected mice from total body irradiation, pointing to potential therapeutic applications. Tissue damage induced by ionizing radiation in the hematopoietic and gastrointestinal systems is the major cause of lethality in radiological emergency scenarios and underlies some deleterious side effects in patients undergoing radiation therapy1,2. The identification of target-specific interventions that confer radiomitigating activity is an unmet challenge. Here we identify the thrombomodulin (Thbd)–activated protein C (aPC) pathway as a new mechanism for the mitigation of total body irradiation (TBI)-induced mortality. Although the effects of the endogenous Thbd-aPC pathway were largely confined to the local microenvironment of Thbd-expressing cells, systemic administration of soluble Thbd or aPC could reproduce and augment the radioprotective effect of the endogenous Thbd-aPC pathway. Therapeutic administration of recombinant, soluble Thbd or aPC to lethally irradiated wild-type mice resulted in an accelerated recovery of hematopoietic progenitor activity in bone marrow and a mitigation of lethal TBI. Starting infusion of aPC as late as 24 h after exposure to radiation was sufficient to mitigate radiation-induced mortality in these mice. These findings suggest that pharmacologic augmentation of the activity of the Thbd-aPC pathway by recombinant Thbd or aPC might offer a rational approach to the mitigation of tissue injury and lethality caused by ionizing radiation.

The introduction of immunomodulatory drugs (IMiDs) has improved clinical outcome in patients with multiple myeloma (MM). However, their use has been associated with a higher risk of cardiovascular complications. The use of IMiDs with dexamethasone, chemotherapy, or in combination with erythropoietic agents enhances the risk of venous thromboembolism (VTE) up to 25%. The pathogenesis of this increased risk of VTE seen with IMiD-based combination therapy is not yet fully understood, but several mechanisms have been proposed to explain the development of this hypercoagulable state. In cancer patients, prothrombotic factors include age, chemotherapy, immobility, enhanced expression of tissue factor of malignant cells, circulating microparticles, and increased vascular endothelial growth factor (VEGF). In patients with paraproteinemias, immunoglobulin-specific mechanisms may also be involved and include hypofibrinolysis, hyperviscosity, procoagulant autoantibody production, effects of inflammatory cytokines, and acquired activated protein C resistance (APCR). In this review we will focus on IMiD-associated effects on specific thrombotic mechanisms.

1 Background: CTCs are promising biomarkers in mCRPC, and telomerase activity (TA) is a recognized cancer marker. In this phase III trial we analyzed CTCs using 2 methods: CellSearch for fixed cell enumeration, and a novel Parylene-C slot filter for live CTC capture and TA measurement. Methods: Blood samples (7.5 ml) were drawn at baseline (d1) and pre-cycle 2 (d21) of Rx and shipped overnight for central processing. For CellSearch enumeration, Cox regression was used to evaluate the association between OS, baseline CTC counts, and CTC dynamics (d1 to d21). For TA, filter-trapped cells were lysed and assayed for TA using qPCR-based telomeric repeat amplification. Cox regression evaluated the association between OS and TA overall and within subgroups characterized by good vs. poor (<5 vs. >=5) prognosis baseline CTC counts. For all measurements, receiver operator characteristic (ROC) analysis and characteristics and regression trees (CART) were used to explore further prognostic cutpoints. Results: Samples were obtained from 263 men. Median d1 CTC count was 5, and there was a significant difference in OS for d1 CTC < vs. >=5, hazard ratio (HR) 2.92 (p<0.001) after adjustment for other factors. D1 CTC and OS had ROC AUC of 0.781. In men with low d1 CTC (< 5), an increase in CTC was associated with shorter OS, HR 4.04 (p=0.004); in men with high d1 CTC (>=5), a >=2-fold decrease in CTC was associated with longer OS, HR 0.45 (p=0.012); adjusting for risk factors. For TA, men with baseline CTC >=5 (41% of cohort) who had high CTC TA had HR 1.14 (p<0.005) for OS after adjustment for other factors including CTC counts. CART identified additional risk subgroups based on CTC counts and TA. Conclusions: In this phase III trial, d1 CTC and d1 to d21 CTC dynamics were prognostic of OS after risk factor adjustment, comprising the largest docetaxel-based prospective cohort to date which validates a 5 CTC prognostic threshold and identifies new potentially useful enumeration subgroups. In men with CTCs >=5, TA from cells live-captured on a new slot filter constitutes the first CTC-derived biomarker prognostic of OS in a prospective clinical trial.

10503 Background: CTC are promising biomarkers in mCRPC but have not been prospectively validated for docetaxel treatment (Rx). Using CellSearch technology (J&J), we enumerated CTC in this Phase 3 trial & assessed prognostic value for OS. The aim of this correlative study nested within 0421 was to compare CTC via CellSearch technology to newer microfilter technologies (Cote & Goldkorn PIs RO1 CA141077). Comparative data analysis is ongoing. Methods: CTC were drawn at baseline (d1) & pre-cycle 2 (d21) of Rx & shipped overnight to a central site for enumeration (CTC/7.5 ml). Cox regression evaluated the association between OS and (i) baseline CTC counts & (ii) CTC dynamics (d1 to d21) in pts with good (<5) vs. poor (>=5) baseline CTC counts. Receiver operator characteristic (ROC) analysis and Characteristics & Regression Trees (CART) were used to explore further prognostic CTC cutpoints for 2-yr survival. Results: Of 263 patients (pts) consented, 238 were evaluable at d1 & 232 at d21. At d1 median CTC was 5 (range 0-5916) & d1 CTC < vs. >= 5 was associated with baseline PSA (mean 99 vs. 320 ng/ml, p=0.004) and worse bone pain (36% vs. 51%, p=0.03). There was a significant difference in OS for d1 CTC < vs. >=5, with a hazard ratio (HR) of 2.92 (95% CI 1.92-4.43, p<0.001) after adjustment for PSA & other factors. In pts with low d1 CTC (< 5), an increase in CTC was associated with shorter OS, HR 4.04 (95%CI 1.56-10.44, p=0.004); in pts with high d1 CTC (>=5), a >=2-fold decrease in CTC was associated with longer OS, HR 0.45 (95%CI 0.24-0.84, p=0.012); adjusting for risk factors. D1 CTC and 2-year survival had ROC AUC of 0.781. CART analysis identified prognostic subgroups based on CTC of 0, 1-5, 6-53, and >53: (HR 0.36, 0.77,1.3 and 2.8). Conclusions: In this phase 3 trial, d1 CTC was prognostic of OS after risk factor adjustment. CTC dynamics from d1 to d21 were also prognostic of OS. These data are an exploratory subset analysis of the overall study. Yet, they comprise the largest docetaxel-based prospective cohort to date, which validates a 5 CTC prognostic threshold for OS & identifies new potential prognostic subgroups that may extend the clinical utility of CTC enumeration in mCRPC.

Purpose: To determine, using a specific small-molecule inhibitor of protease-activated receptor 1 (PAR1) signaling, whether the beneficial effect of thrombin inhibition on radiation enteropathy development is due to inhibition of blood clotting or to cellular (PAR1-mediated) thrombin effects.Methods and Materials: Rats underwent fractionated X-irradiation (5 Gy x 9) of a 4-cm small-bowel segment. Early radiation toxicity was evaluated in rats receiving PAR1 inhibitor (SCH602539, 0, 10, or 15 mg/kg/d) from 1 day before to 2 weeks after the end of irradiation. The effect of PAR1 inhibition on development of chronic intestinal radiation fibrosis was evaluated in animals receiving SCH602539 (0, 15, or 30 mg/kg/d) until 2 weeks after irradiation, or continuously until termination of the experiment 26 weeks after irradiation.Results: Blockade of PAR1 ameliorated early intestinal toxicity, with reduced overall intestinal radiation injury (P=.002), number of myeloperoxidase-positive (P=.03) and proliferating cell nuclear antigen-positive (P=.04) cells, and collagen III accumulation (P=.005). In contrast, there was no difference in delayed radiation enteropathy in either the 2- or 26-week administration groups.Conclusion: Pharmacological blockade of PAR1 seems to reduce early radiation mucositis but does not affect the level of delayed intestinal radiation fibrosis. Early radiation enteropathy is related to activation of cellular thrombin receptors, whereas platelet activation or fibrin formation may play a greater role in the development of delayed toxicity. Because of the favorable side-effect profile, PAR1 blockade should be further explored as a method to ameliorate acute intestinal radiation toxicity in patients undergoing radiotherapy for cancer and to protect first responders and rescue personnel in radiologic/nuclear emergencies. (c) 2013 Elsevier Inc.

Sepsis is the leading cause of mortality in intensive care units. Early detection and intervention are critical to prevent death. The acute radiation syndrome is characterized by damage of the gastrointestinal and hematopoietic systems. Translocation of intestinal microflora combined with immune system compromise may lead to septicemia and death. This work examined the utility of procalcitonin, a clinical sepsis biomarker, in a mouse model of radiation toxicity. C57/BL6 mice were exposed to total body irradiation (TBI). Intestinal mucosal permeability was measured in vivo, and liver bacterial load and plasma levels of procalcitonin (PCT), lipopolysaccharide (LPS), and LPS-binding protein were measured at baseline and at 3.5, 7, and 10 days after TBI. The value of early PCT in predicting subsequent lethality was determined by receiver operating characteristic analysis. Four days after TBI, a dose-dependent increase in permeability of the intestinal mucosa was observed, whereas bacterial translocation was present from day 7 onward. There was a high positive correlation between bacterial translocation and all sepsis biomarkers, with PCT exhibiting the strongest correlation. Moreover, plasma PCT levels were elevated already from day 3.5 onward, whereas LPS was elevated from day 7 and LPS-binding protein only 10 days after TBI. Receiver operating characteristic analysis revealed that PCT levels measured 3.5 days after TBI predicted lethality at 10 days. These data demonstrate the value of PCT as an early biomarker in radiation-induced bacteremia for mouse studies and suggest that clinical results from other septic conditions may apply to postradiation septicemia in humans.

Increased risk of venous thromboembolism (VTE) has been described in multiple myeloma patients, particularly when exposed to immunomodulatory drugs. Epidemiological studies have shown that monoclonal gammopathy of undetermined significance (MGUS) patients also have an increased risk of VTE compared with normal individuals. Acquired activated protein C resistance (APC-R) is an independent risk factor for VTE in hematologic malignancies. We reviewed the records of patients with multiple myeloma and MGUS for APC-R by PEFAKIT APC-R test and compared them to normal individuals. We excluded from the analysis patients with a documented factor V Leiden mutation. The PEFAKIT APC-R is a plasma-based functional prothrombin assay based on ratio of patient clotting time with and without APC. Thirty-three MGUS and 93 multiple myeloma patients were compared with 39 normal individuals. Baseline characteristics from the three groups were similar in terms of age, sex, and performance status. The median APC-R for multiple myeloma, MGUS, and controls were 1, 1.06, and 1.1, respectively. Multiple myeloma patients compared to normal individuals had significantly shorter APC-R (P=0.0012). No significant difference was observed between MGUS and normal individuals (P=0.17). After analyzing APC-R values and multiple coagulation parameters, a significant inverse correlation was found between APC-R and fibrinogen (P=0.0000001) and D-dimer (P=0.045) serum levels and a direct correlation with prothrombin time value (P=0.034). The Pefakit APC-R test measured as continuous variable shows a statistically significant decrease in patients with myeloma compared to normal individuals.

166 Background: Recent data suggest that circulating tumor cell (CTC) enumeration is a surrogate predictive endpoint for survival in metastatic castration-resistant prostate cancer (mCRPC). Data supporting the notion of changing therapy from docetaxel based on CTC numbers is limited in PC, due to a limited experience with second-line systemic therapies following docetaxel failure. Methods: Peripheral blood from patients receiving cyclophosphamide following progression on docetaxel was analyzed by CellSearch Methodology (Veridex, LLC; Warren NJ) enumerate CTC. Circulating tumor cells were enumerated prior to and at least three weeks following the initiation of cyclophosphamide. Patients were categorized as responsive, defined as a follow up CTC of <5 cells or a greater than a 90% decline in counts between CTC determinations, or refractory (all others). Cyclophosphamide responsiveness was then correlated with docetaxel responsiveness using a Fisher-exact test. Results: Twenty two patients received oral cyclophosphamide therapy (50-150 mg/day). Of these, twelve (55%) were clinically primary docetaxel refractory, assessed by either clinical or PSAWG2 criteria while on docetaxel, and ten (45%) were initially responsive but subsequently progressed on docetaxel. Of the twelve patients who were primarily refractory to docetaxel, seven (58%) exhibited a cyclophosphamide response. In the majority of these cases, this response was durable with a complete disappearance of CTC. Conversely, only one patient (10%) who initially responded to docetaxel was sensitive to cyclophosphamide (P=0.031). Conclusions: Using a CTC endpoint cyclophosphamide appears to be active in patients initially refractory to docetaxel, but not those who initially responded. These data support the further evaluation of the potential for selective clinical utility of cyclophosphamide as second-line chemotherapy. [Table: see text]

Amyloidosis is a disease characterized by aberrant precursor molecules whose misfolded intermediate forms aggregate and are deposited as interstitial fibrils. The most common type of systemic amyloidosis is immunoglobulin light-chain amyloidosis (AL). Less common types of systemic amyloidosis are the transthyretin (ATTR) types caused by either mutant (hereditary) variants or wild-type ("senile systemic") transthyretin. Although rare in developed countries secondary amyloidosis is associated with autoimmune or inflammatory diseases, chronic infections and malignancies. Different precursor proteins can coexist in the same patient as in the African-American population, which has a 4% incidence of an hereditary ATTR variant (Val122Ile) and a significant incidence of monoclonal gammopathy (1, 2). The amyloids are highly ordered cross-┚ sheet protein with extra cellular deposition in single or multiple organs. Cardiac deposition, leading to an infiltrative/restrictive cardiomyopathy, is a common feature and may be present at the diagnosis or discovered while investigating a patient presenting with non-cardiac amyloidosis. AL amyloidosis, is associated with clinical cardiac involvement in about half of all cases, although subclincal involvement may be detected in almost every case at autopsy on endomyocardial biopsy. Laser micro dissection with mass spectrometry assessing the constituents of the Congophilic deposits is now the gold standard for amyloid typing, obtaining protein type identification in over 98% of cases (3). Evaluation for cardiac involvement is a critical step of the initial staging of amyloidosis. Criteria for the assessment of organ involvement at baseline and after treatment have been standardized (4). In systemic AL amyloidosis the extent of cardiac involvement has prognostic indications, with a median survival of 6 months for untreated or non-responding patients (5, 6).

BACKGROUND:Sall4 is a key factor for the maintenance of pluripotency and self-renewal of embryonic stem cells (ESCs). Our previous studies have shown that Sall4 is a robust stimulator for human hematopoietic stem and progenitor cell (HSC/HPC) expansion. The purpose of the current study is to further evaluate how Sall4 may affect HSC/HPC activities in a murine system.METHODS:Lentiviral vectors expressing Sall4A or Sall4B isoform were used to transduce mouse bone marrow Lin-/Sca1+/c-Kit+ (LSK) cells and HSC/HPC self-renewal and differentiation were evaluated.RESULTS:Forced expression of Sall4 isoforms led to sustained ex vivo proliferation of LSK cells. In addition, Sall4 expanded HSC/HPCs exhibited increased in vivo repopulating abilities after bone marrow transplantation. These activities were associated with dramatic upregulation of multiple HSC/HPC regulatory genes including HoxB4, Notch1, Bmi1, Runx1, Meis1 and Nf-ya. Consistently, downregulation of endogenous Sall4 expression led to reduced LSK cell proliferation and accelerated cell differentiation. Moreover, in myeloid progenitor cells (32D), overexpression of Sall4 isoforms inhibited granulocytic differentiation and permitted expansion of undifferentiated cells with defined cytokines, consistent with the known functions of Sall4 in the ES cell system.CONCLUSION:Sall4 is a potent regulator for HSC/HPC self-renewal, likely by increasing self-renewal activity and inhibiting differentiation. Our work provides further support that Sall4 manipulation may be a new model for expanding clinically transplantable stem cells.

BACKGROUND:Infantile hemangiomas (IH) are the most common benign tumors of infancy. The typical clinical course consists of rapid growth during the first year of life, followed by natural and gradual involution over a multi-year time span through unknown cellular mechanisms. Some tumors respond to medical treatment with corticosteroids or beta-blockers, however, when this therapy fails or is incomplete, surgical extirpation may be necessary. Noninvasive therapies to debulk or eliminate these tumors would be an important advance. The development of an in vitro cell culture system and an animal model would allow new insights into the biological processes involved in the development and pathogenesis of IH.RESULTS:We observed that proliferative stage IH specimens contain significantly more SALL4+ and CD133+ cells than involuting tumors, suggesting a possible stem cell origin. A tumor sphere formation assay was adapted to culture IH cells in vitro. Cells in IH tumor spheres express GLUT1, indicative of an IH cell of origin, elevated levels of VEGF, and various stem/progenitor cell markers such as SALL4, KDR, Oct4, Nanog and CD133. These cells were able to self-renew and differentiate to endothelial lineages, both hallmarks of tumor stem cells. Treatment with Rapamycin, a potent mTOR/VEGF inhibitor, dramatically suppressed IH cell growth in vitro. Subcutaneous injection of cells from IH tumor spheres into immunodeficient NOD-SCID mice produced GLUT1 and CD31 positive tumors with the same cellular proliferation, differentiation and involution patterns as human hemangiomas.CONCLUSIONS:The ability to propagate large numbers of IH stem cells in vitro and the generation of an in vivo mouse model provides novel avenues for testing IH therapeutic agents in the future.

Little information exists regarding the utility circulating tumor cell (CTC) enumeration in hormone sensitive prostate cancer. We enumerated CTC in 33 consecutive patients undergoing androgren deprivation therapy (ADT) at our institution. Multivariate analysis revealed baseline CTC as the only independent predictor of progression to CRPC. These data suggest that baseline CTC may identify those unlikely to benefit from ADT.Introduction: Circulating tumor cell (CTC) enumeration by using the Cellsearch platform has established prognostic and predictive value in patients with metastatic castration-resistant prostate cancer (mCRPC). Limited information exists regarding the clinical utility of CTC enumeration in metastatic hormone-sensitive prostate cancer (mHSPC). The goal of this study was to prospectively determine the relative clinical utility of CTCs in mHSPC. Patients and Methods: We analyzed serial CTC in conjunction with other classic biomarkers in 33 consecutive patients treated at the Nevada Cancer Institute with HSPC initiating androgen deprivation therapy and correlated these patients with prognostic prostate-specific antigen (PSA) endpoints and onset of CRPC. Results: Initial CTC correlated positively with lactate dehydrogenase and alkaline phosphatase, and were unrelated to PSA and testosterone. In univariate analysis, baseline CTC, alkaline phosphatase, lactate dehydrogenase, testosterone, and follow-up CTC were individual predictors of progression to CRPC. In a multivariate Cox regression, only baseline CTC retained independent predictive value. Threshold analysis revealed the cutpoint that optimized specificity and sensitivity of the test to be 3 cells per 7.5 mL whole blood. Baseline CTC also correlated well with PSA nadir benchmarks. Conclusions: Initial CTC values predict the duration and magnitude of response to hormonal therapy. CTC enumeration may identify patients at risk of progression to CRPC before initiation of androgen deprivation therapy.

Patients with multiple myeloma (MM) are at elevated risk of venous thromboembolism (VTE), specifically deep vein thrombosis (DVT) and pulmonary embolism (PE). VTE risk in MM is increased by various patient- and disease-related factors. The type of anti-MM therapy represents a key factor, with a substantially elevated VTE risk in patients treated with the immunomodulatory drugs (IMiDs) thalidomide or lenalidomide in combination with dexamethasone and/or chemotherapy; VTE risk with lenalidomide-dexamethasone is further increased with concomitant erythropoietin. By contrast, treatment with the proteasome inhibitor bortezomib, alone or in combination, does not increase VTE risk; rates of DVT/PE do not appear affected by the use of erythropoiesis-stimulating agents. Bortezomib has shown antihemostatic effects in patients with relapsed or refractory MM, which supports that it exerts antithrombotic actions and thus potentially provides a protective effect in combination with regimens with an elevated VTE risk. Herein, we review data from phase 3 trials of bortezomib- and/or IMiD-based therapy in frontline MM, together with other studies of novel combination regimens. Despite the confounding effect of variable VTE prophylaxis, bortezomib-based regimens were typically associated with DVT/PE rates of ≤5%, similar to those seen with melphalan-prednisone and dexamethasone, whereas IMiD-based bortezomib-free regimens were generally associated with higher rates. Direct comparisons of regimens of thrombogenic potential with or without bortezomib demonstrated lower VTE risk with bortezomib. Between-study comparisons of VTE risk support these findings. Taken together, these data confirm the low VTE risk associated with bortezomib and support a potential protective effect of bortezomib in combination with IMiD-based regimens associated with elevated VTE risk.

Our aim was to determine the utility of circulating micro RNA miR-141 as a potential biomarker of therapeutic response in prostate cancer (CaP) patients. We compared the values of miR-141 in plasma of 21 CaP patients to the levels of prostate specific antigen (PSA), circulating tumor cells (CTC) and lactate dehydrogenase (LDH). Data suggest a strong correlation of miR-141 values and clinical course. For prostate cancer (CaP), the measurement of prostate-specific antigen (PSA) and radiographic studies do not adequately predict response to therapy and survival, and, therefore, new relevant biomarkers are needed. We and other researchers have shown that longitudinal measurements of PSA, circulating tumor cells (CTC), and lactate dehydrogenase (LDH) may aid in predicting response to therapy. Results of recent studies have determined that circulating microRNA (miRNA) miR-141 is detected in plasma of patients with CaP. We, therefore, compared the temporal changes of miR-141 with the levels of CTC, LDH, and PSA in 21 patients with CaP, and longitudinally examined these markers alone or in combinations to determine the utility of miR-141 in the predicting a patient's clinical course and response to therapy. Levels of miR-141 in plasma of 21 patients with CaP were measured by using quantitative reverse transcription-polymerase chain reaction. A total of 35 intervals were assessed. Directional changes (increasing or decreasing) in PSA, CTC, and miR-141 had sensitivity in predicting clinical outcome (progression vs. nonprogressing) of 78.9%. Logistic regression modeling of the probability of clinical progression demonstrates that miR-141 levels predicted clinical outcomes with an odds ratio of at least 8.3. miR-141 also had the highest correlation with temporal changes of PSA with a correlation of R = 0.77 (P < .001). In this retrospective study, miR-141 demonstrated a similar ability to predict clinical progression when compared with other clinically validated biomarkers. Furthermore, miR-141 demonstrated high correlation with changes of the other biomarkers.

Induced pluripotent stem (iPS) cells are derived from reprogrammed somatic cells and are similar to embryonic stem (ES) cells in morphology, gene/protein expression, and pluripotency. In this study, we explored the potential of iPS cells to differentiate into alveolar Type II (ATII)-like epithelial cells. Analysis using quantitative real time polymerase chain reaction and immunofluorescence staining showed that pulmonary surfactant proteins commonly expressed by ATII cells such as surfactant protein A (SPA), surfactant protein B (SPB), and surfactant protein C (SPC) were upregulated in the differentiated cells. Microphilopodia characteristics and lamellar bodies were observed by transmission electron microscopy and lipid deposits were verified by Nile Red and Periodic Acid Schiff staining. C3 complement protein, a specific feature of ATII cells, was present at high levels in culture supernatants demonstrating functionality of these cells in culture. These data show that the differentiated cells generated from iPS cells using a culture method developed previously (Rippon et al., 2006) are ATII-like cells. To further characterize these ATII-like cells, we tested whether they could undergo epithelial to mesenchymal transition (EMT) by exposure to drugs that induce lung fibrosis in mice, such as bleomycin, and the combination of transforming growth factor beta1 (TGF(b1)) and epidermal growth factor (EGF). When the ATII-like cells were exposed to either bleomycin or a TGF(b1)-EGF cocktail, they underwent phenotypic changes including acquisition of a mesenchymal/fibroblastic morphology, upregulation of mesenchymal markers (Col1, Vim, a-Sma, and S100A4), and downregulation of surfactant proteins and E-cadherin. We have shown that ATII-like cells can be derived from skin fibroblasts and that they respond to fibrotic stimuli. These cells provide a valuable tool for screening of agents that can potentially ameliorate or prevent diseases involving lung fibrosis.