Relapse of Acquired Hemophilia A after COVID-19 Infection.

Acquired hemophilia A (AHA) is a rare disease in which an autoantibody causes bleeding by interacting with and inhibiting the coagulation activity of endogenous factor VIII (FVIII). Most cases of AHA are idiopathic; known causes include autoimmune diseases, malignant tumors, pregnancy, drugs, and viral infections. An 86-year-old man was diagnosed with AHA based on the following results: an activated partial thromboplastin time (aPTT) extension of 130.7 seconds, presence of an inhibitor pattern in a mixing study, an endogenous factor VIII (FVIII) level of <1%, and an FVIII inhibitor titer of >5.1 Bethesda units (BU). The activity of von Willebrand factor (vWF) was diminished (<10%), which was considered a complication of acquired von Willebrand syndrome (AVWS). The patient was started on prednisolone, and the inhibitor level eventually became negative. vWF values also became normal. However, 1 year later, he was hospitalized for treatment of coronavirus disease 2019 (COVID-19). Blood testing showed an aPTT extension of 110.5 seconds, FVIII level of 4%, and FVIII inhibitor titer of 0.8 BU; thus, a relapse of AHA was diagnosed. After administration of corticosteroid and remdesivir, he recovered from COVID-19 and AHA. The inhibitor level became negative on the 9th day of admission. Several studies have implicated COVID-19 infection and vaccination in AHA. We recommend that aPTT be measured when patients with AHA are infected with SARS-CoV2, to confirm AHA relapse.

Safety and efficacy of high-dose cytarabine MEAM therapy and other treatments for auto-peripheral blood stem cell transplantation: A retrospective comparative study.

AIM: The MEAM regimen consisting of ranimustine (MCNU), etoposide (ETP), cytarabine (Ara-C), and melphalan (MEL) is widely used before auto-peripheral blood stem cell transplantation (auto-PBSCT) for malignant lymphoma in Japan. The MEAM regimen generally consists of 200-400 mg/m2 for 4 days, but we decided to increase the dosage of Ara-C from the standard to 2 g/m2 for 2 days with the aim of increasing drug transferability to the central nervous system. We evaluate the safety and therapeutic efficacy of high-dose Ara-C MEAM therapy. METHODS: The high-dose Ara-C MEAM protocol consisted of MCNU 300 mg/m2 on day -7, ETP 200 mg/m2 on days -6, -5, -4, -3 and Ara-C 2 g/m2 on day -4 -3, and MEL 140 mg/m2 on day -2. We retrospectively analyzed 37 cases of malignant lymphoma at our institution between May 2014 and July 2020. RESULTS: All patients got engraftment and there were no cases of treatment-related mortality. In all cases, the 3-year overall survival (OS) and progression-free survival (PFS) after transplantation were 80.6% and 65.7%, respectively. Twenty-one cases of diffuse large B-cell lymphoma recurrence, for which there is proven usefulness of auto-PBSCT, showed good results after transplantation, with the 3-year OS and PFS after transplantation being 100% and 74.3%, respectively. CONCLUSION: The safety and efficacy of high-dose Ara-C MEAM therapy were demonstrated, but the expected therapeutic effect on central nervous system lesions could not be fully evaluated owing to the small number of cases.

Systematic identification of intron retention associated variants from massive publicly available transcriptome sequencing data.

Many disease-associated genomic variants disrupt gene function through abnormal splicing. With the advancement of genomic medicine, identifying disease-associated splicing associated variants has become more important than ever. Most bioinformatics approaches to detect splicing associated variants require both genome and transcriptomic data. However, there are not many datasets where both of them are available. In this study, we develop a methodology to detect genomic variants that cause splicing changes (more specifically, intron retention), using transcriptome sequencing data alone. After evaluating its sensitivity and precision, we apply it to 230,988 transcriptome sequencing data from the publicly available repository and identified 27,049 intron retention associated variants (IRAVs). In addition, by exploring positional relationships with variants registered in existing disease databases, we extract 3,000 putative disease-associated IRAVs, which range from cancer drivers to variants linked with autosomal recessive disorders. The in-silico screening framework demonstrates the possibility of near-automatically acquiring medical knowledge, making the most of massively accumulated publicly available sequencing data. Collections of IRAVs identified in this study are available through IRAVDB ( https://iravdb.io/ ).

Cyclophosphamide-induced cardiotoxicity at conditioning for allogeneic hematopoietic stem cell transplantation would occur among the patients treated with 120 mg/kg or less.

Cyclophosphamide (CY)-induced cardiotoxicity involves rare lethal complications. We previously reported the cardiac events of 811 allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients; 12 out of 811 recipients (1.5%) developed fatal heart failure. The mortality rate was also very high (91.6%, 11/12). CY dose (200 mg/kg or more) was reported as the independent risk factor. The main disease in patients treated with 200 mg/kg or more of CY was severe aplastic anemia (AA). Therefore, we reduced the dose of CY during conditioning for AA (from 200 to 100 mg/kg), and then we analyzed the clinical features of 294 patients who received a total dose of at least 100 mg/kg of CY. We also compared the clinical features between the current study and our previous study. The proportion of patients treated with at least 200 mg/kg of CY was reduced from 4.2% to 0%. However, CY-induced heart failure occurred in four of the 294 patients (1.4%), which was similar to the finding reported in our previous study (1.5%). Two of these four patients received a post-transplant CY (PTCy) regimen (CY 100 mg/kg). All four patients were treated in the cardiac intensive care unit (C-ICU), and two patients survived. In summary, even the CY dose of 120 mg/kg or less would cause cardiotoxicity. We should also carefully monitor patients treated with PTCy, considering the possibility of CY-induced cardiotoxicity. Early diagnosis and ICU management have contributed to improved outcomes.

Prognostic impact of CEBPA bZIP domain mutation in acute myeloid leukemia.

Mutations of CCAAT/enhancer-binding protein alpha (CEBPAmu) are found in 10% to 15% of de novo acute myeloid leukemia (AML) cases. Double-mutated CEBPA (CEBPAdm) is associated with a favorable prognosis; however, single-mutated CEBPA (CEBPAsm) does not seem to improve prognosis. We investigated CEBPAmu for prognosis in 1028 patients with AML, registered in the Multi-center Collaborative Program for Gene Sequencing of Japanese AML. It was found that CEBPAmu in the basic leucine zipper domain (bZIP) was strongly associated with a favorable prognosis, but CEBPAmu out of the bZIP domain was not. The presence of CEBPAmu in bZIP was a strong indicator of a higher chance of achieving complete remission (P < .001), better overall survival (OS; P < .001) and a lower risk of relapse (P < .001). The prognostic significance of CEBPAmu in bZIP was also observed in the subgroup with CEBPAsm (all patients: OS, P = .008; the cumulative incidence of relapse, P = .063; patients aged ≤70 years and with intermediate-risk karyotype: OS, P = .008; cumulative incidence of relapse, P = .026). Multivariate analysis of 744 patients aged ≤70 years showed that CEBPAmu in bZIP was the most potent predictor of OS (hazard ratio, 0.3287; P < .001). CEBPAdm was validated as a cofounding factor, which was overlapping with CEBPAmu in bZIP. In summary, these findings indicate that CEBPAmu in bZIP is a potent marker for AML prognosis. It holds potential in the refinement of treatment stratification and the development of targeted therapeutic approaches in CEBPA-mutated AML.

Structural basis of cytokine-mediated activation of ALK family receptors.

Anaplastic lymphoma kinase (ALK)1 and the related leukocyte tyrosine kinase (LTK)2 are recently deorphanized receptor tyrosine kinases3. Together with their activating cytokines, ALKAL1 and ALKAL24-6 (also called FAM150A and FAM150B or AUGß and AUGα, respectively), they are involved in neural development7, cancer7-9 and autoimmune diseases10. Furthermore, mammalian ALK recently emerged as a key regulator of energy expenditure and weight gain11, consistent with a metabolic role for Drosophila ALK12. Despite such functional pleiotropy and growing therapeutic relevance13,14, structural insights into ALK and LTK and their complexes with cognate cytokines have remained scarce. Here we show that the cytokine-binding segments of human ALK and LTK comprise a novel architectural chimera of a permuted TNF-like module that braces a glycine-rich subdomain featuring a hexagonal lattice of long polyglycine type II helices. The cognate cytokines ALKAL1 and ALKAL2 are monomeric three-helix bundles, yet their binding to ALK and LTK elicits similar dimeric assemblies with two-fold symmetry, that tent a single cytokine molecule proximal to the cell membrane. We show that the membrane-proximal EGF-like domain dictates the apparent cytokine preference of ALK. Assisted by these diverse structure-function findings, we propose a structural and mechanistic blueprint for complexes of ALK family receptors, and thereby extend the repertoire of ligand-mediated dimerization mechanisms adopted by receptor tyrosine kinases.

Cell sorting and germ layer formation in reconstructed starfish embryos.

Germ layer formation is driven by embryonic cell sorting during the early developmental stages. Starfish (Patiria pectinifera) embryos have a connected endoderm and ectoderm, albeit with few contact surfaces between the epithelia. To better understand the association between cell sorting and germ layer formation, we reconstructed P. pectinifera embryos and examined their germ layer formation. Initial observations showed that the presumptive endodermal (pEN) and presumptive ectodermal (pEC) portions of the embryonic body at the late-blastula stage were preserved throughout development. Based on this, cells that were dissociated from each dermal fragment were mixed in a reconstruction experiment. Our results showed that the pEN and pEC cells were located inside and outside the reaggregates, respectively, to form an embryonic body containing two epithelial layers, separated by a blastocoel. During this process, the pEN cells were motile and shifted from smaller clumps to form a large clump. In contrast, in reaggregates formed in separate cultures, the pEN cells showed strong adhesion abilities, whereas the pEC cells underwent epithelialization. Unlike that in pEN cells, the reaggregation of pEC cells preceded cadherin expression. Filamentous actin was similarly observed in both reaggregates. These results suggest that during the reconstruction of starfish embryos, germ layer formation occurs via the sorting of pEN and pEC cells, depending on their adhesiveness, motility, and epithelialization. In vivo, these properties might embody the physiological significance of cell adhesion in the germ layers constituting the epithelial monolayer.

Presence of Promyelocytes in Peripheral Blood as a Novel Predictor of Optimal Timing for Single-Step Peripheral Blood Stem Cell Collection.

BACKGROUND: Because peripheral blood stem cell (PBSC) collection places a burden on the patient and should ideally be completed in a single procedure, a convenient clinical predictive factor is needed. METHODS: This retrospective study included 72 patients who underwent autologous PBSC collection. A median volume of 3.9 × 106 CD34-positive cells/kg (range: 0.3-47.4 × 106 cells/kg) was collected on the first day. We defined failure as inability to collect 2.0 × 106 cells/kg on the first day. PBSC collection was classified as failed (n = 25, 34.7%) and successful (n = 47, 65.3%), and patient clinical characteristics were analyzed. RESULTS: The success group had significantly more cases in which a differential white blood cell count in peripheral blood on the day of PBSC collection detected promyelocytes (n = 34 [72.3%] vs. n = 11 [44.0%] in the failure group; P = 0.008). Sixty-two patients underwent autologous PBSC transplantation (median number of transplanted cells, 5.6 × 106/µL; range: 1.60-47.4 × 106 cells/µL). Among transplanted patients, the success and failure groups did not significantly differ in relation to the interval until neutrophil, platelet, or red blood cell engraftment. CONCLUSION: The presence of promyelocytes in peripheral blood may be a useful indicator of the optimal timing for single-step PBSC collection.

The sensitivity of the FLT3-ITD detection method is an important consideration when diagnosing acute myeloid leukemia.

Fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) is a key predictive factor for the prognosis of acute myeloid leukemia (AML). We compared the detection sensitivity of fragment analysis with that of PCR-electrophoresis using MV4-11 (FLT3-ITD) and NKM-1 (FLT3-wild type) cell lines. DNA of these cells was mixed at different ratios and subjected to PCR-electrophoresis or fragment analysis. PCR-electrophoresis was found to have an FLT3-ITD allelic ratio (AR) detection limit of 0.034-0.072. Visual inspection of the PCR-electrophoresis revealed a lower detection sensitivity than that of fragment analysis. Therefore, it is essential to conduct fragment analysis when screening for FLT3-ITD.

Outcomes of Patients with Early Hyperbilirubinemia after Allogeneic Hematopoietic Stem Cell Transplantation.

BACKGROUND: Because the cause of liver dysfunction after allogeneic hematopoietic stem cell transplantation (HSCT) is difficult to identify in the early stages, treatment may be delayed. Therefore, early factors associated with unfavorable outcomes of liver dysfunction must be identified. The objective of this study was to identify unfavorable prognostic factors for liver dysfunction during the early period after transplantation. METHODS: We defined liver dysfunction as elevated liver or biliary enzyme levels (corresponding to Grade 2 in the Common Terminology Criteria for Adverse Events version 4.0) within 30 days of transplantation and retrospectively investigated data from 82 patients who had undergone allogeneic HSCT at our center. RESULTS: Elevated liver or biliary enzyme levels were observed in almost half of the patients studied (n=40, 48.7%). Elevated total bilirubin (T-Bil) level was the most frequently observed unfavorable prognostic factor and had the greatest effect on overall survival (OS), progression-free survival (PFS), and non-relapse mortality (NRM) (probability of unfavorable outcome in patients without and with elevated T-Bil level: OS, 58.9% vs. 15.4%, p < 0.001; PFS, 46.4% vs. 15.4%, p < 0.001; NRM, 10.7% vs. 53.8%, p < 0.001). Moreover, the probability of an unfavorable outcome increased in relation to the degree of T-Bil elevation and absence of improvement over time in T-Bil level. CONCLUSION: Elevated T-Bil level was an important marker of outcomes for liver dysfunction after allogeneic HSCT.

Risk Factors for Acute Kidney Injury and Chronic Kidney Disease following Allogeneic Hematopoietic Stem Cell Transplantation for Hematopoietic Malignancies.

BACKGROUND: Acute kidney injury (AKI) and chronic kidney disease (CKD) are considered common complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT). OBJECTIVES AND METHOD: In this study, 114 patients who had undergone allo-HSCT were retrospectively analyzed to investigate the risk factors for onset of posttransplant AKI and CKD as defined by the new Kidney Disease Improving Global Outcomes criteria. RESULTS: Seventy-four patients (64.9%) developed AKI and 25 (21.9%) developed CKD. The multivariate analysis showed that the risk factors for developing stage 1 or higher AKI were age ≥46 years at the time of transplant (p = 0.001) and use of ≥3 nephrotoxic drugs (p = 0.036). For CKD, the associated risk factors were disease status other than complete remission at the time of transplantation (p = 0.018) and onset of AKI after transplant (p = 0.035). The 5-year overall survival (OS) was significantly reduced by development of AKI (p < 0.001), but not CKD. Posttransplant AKI significantly increased the 5-year nonrelapse mortality (p < 0.001), whereas posttransplant CKD showed an increasing tendency, but the difference was not significant. CONCLUSIONS: Posttransplant AKI impacts OS, significantly increases the risk of CKD, and is significantly associated with disseminated intravascular coagulation and use of ˃3 nephrotoxic drugs.

Significance of FLT3-tyrosine kinase domain mutation as a prognostic factor for acute myeloid leukemia.

The prognostic significance of FLT3-tyrosine kinase domain (TKD) mutations remains unknown. To investigate the prognostic impact of FLT3-TKD, 676 de novo acute myeloid leukemia (AML), we retrospectively analyzed cases and conducted a review of the literature. Of the 676 de novo AML cases, 34 (5.0%) were FLT3-TKD-positive; both FLT3-TKD and FLT3-ITD were noted in only two cases (0.3%). Although no significant differences in relapse-free survival (RFS) were noted, FLT3-TKD-positive cases showed better prognoses than FLT3-ITD-positive cases (FLT3-TKD versus FLT3-ITD, p = 0.152). For overall survival (OS), although FLT3-TKD-positive cases showed prognoses similar to those for FLT3-WT cases, their prognoses were significantly better than those of FLT3-ITD-positive cases (FLT3-TKD versus FLT3-ITD, p = 0.032). Moreover, the 5-year OS for FLT3-TKD-positive cases was 46.1%, indicating that this as an intermediate prognosis group. Although no reports from Asia have indicated a frequency of FLT3-TKD-positive cases > 10%, several reports from Europe and the United States have indicated frequencies > 10%. This suggests the possibility that FLT3-TKD-positive cases are less common in Asia than in Europe and the United States. We anticipate that in the future, the appearance of targeting agents, such as FLT3 inhibitors, will improve the prognosis of FLT3-TKD-positive AML relative to that of FLT3-WT AML.

Importance of prognostic stratification via gene mutation analysis in elderly patients with acute myelogenous leukemia.

INTRODUCTION: Acute myelogenous leukemia (AML) in elderly patients is associated with an increased incidence of complications and treatment-related toxicity because of the frequency of comorbid disease and age-related deterioration in organ function. Despite advances in AML treatment in recent years, elderly patients have experienced limited benefit, and their outcomes remain poor. This study aimed to perform a comprehensive gene mutation analysis in elderly AML patients and identify gene mutations that could serve as prognostic factors. METHODS: An analysis of gene mutations was performed for 281 AML patients, including 98 elderly patients aged 65 years or above. RESULTS: Compared to younger AML patients, elderly patients showed a higher frequency of the following gene mutations: TP53 (P = 0.026), PTPN11 (P = 0.006), RUNX1 (P = 0.024), TET2 (P = 0.002), and ASXL1 (P = 0.023). The complete remission rate was significantly lower in DNMT3A mutation-positive cases (4.26%, P = 0.011) and TP53 mutation-positive cases (2.13%, P = 0.031) than in negative cases. The overall survival rate was significantly poorer in cases with FLT3-ITD (P = 0.003), DNMT3A (P = 0.033), or TP53 mutation (P < 0.001). Conversely, cases with PTPN11 mutation (P = 0.014) had a significantly more favorable prognosis. In multivariate analysis, FLT3-ITD (P = 0.011) and TP53 mutation positivity (P = 0.002) were independent poor prognostic factors, as were a performance status of 3 or above (P < 0.001) and poor cytogenetic prognosis (P = 0.001). In contrast, PTPN11 mutation positivity (P = 0.023) was an independent favorable prognosis factor. CONCLUSION: Analysis of gene mutations in elderly AML patients is very important, not only for establishing prognosis, but also for introducing appropriate molecular-targeted treatments.

Prognostic impact of low allelic ratio FLT3-ITD and NPM1 mutation in acute myeloid leukemia.

In the opinion of the European LeukemiaNet (ELN), nucleophosmin member 1 gene mutation (NPM1 mut)-positive acute myeloid leukemia (AML) with an fms-like kinase 3-internal tandem duplication (FLT3-ITD) allele ratio (AR) <0.5 (low AR) has a favorable prognosis, and allogeneic hematopoietic stem cell transplant (allo-HSCT) in the first complete remission (CR1) period is not actively recommended. We studied 147 patients with FLT3-ITD gene mutation-positive AML, dividing them into those with low AR and those with AR of ≥0.5 (high AR), and examined the prognostic impact according to allo-HSCT in CR1. Although FLT3-ITD AR and NPM1 mut are used in the prognostic stratification, we found that NPM1 mut-positive AML with FLT3-ITD low AR was not associated with favorable outcome (overall survival [OS], 41.3%). Moreover, patients in this group who underwent allo-HSCT in CR1 had a significantly more favorable outcome than those who did not (relapse-free survival [RFS] P = .013; OS P = .003). Multivariate analysis identified allo-HSCT in CR1 as the sole favorable prognostic factor (RFS P < .001; OS P < .001). The present study found that prognosis was unfavorable in NPM1 mut-positive AML with FLT3-ITD low AR when allo-HSCT was not carried out in CR1.

Usefulness of BCOR gene mutation as a prognostic factor in acute myeloid leukemia with intermediate cytogenetic prognosis.

BCOR gene is a transcription regulatory factor that plays an essential role in normal hematopoiesis. The wider introduction of next-generation sequencing technology has led to reports in recent years of mutations in the BCOR gene in acute myeloid leukemia (AML), but the related clinical characteristics and prognosis are not sufficiently understood. We investigated the clinical characteristics and prognosis of 377 de novo AML cases with BCOR or BCORL1 mutation. BCOR or BCORL1 gene mutations were found in 28 cases (7.4%). Among cases aged 65 years or below that were also FLT3-ITD-negative and in the intermediate cytogenetic prognosis group, BCOR or BCORL1 gene mutations were observed in 11% of cases (12 of 111 cases), and this group had significantly lower 5-year overall survival (OS) (13.6% vs. 55.0%, P = 0.0021) and relapse-free survival (RFS) (14.3% vs. 44.5%, P = 0.0168) compared to cases without BCOR or BCORL1 gene mutations. Multivariate analysis demonstrated that BCOR mutations were an independent unfavorable prognostic factor (P = 0.0038, P = 0.0463) for both OS and RFS. In cases of AML that are FLT3-ITD-negative, aged 65 years or below, and in the intermediate cytogenetic prognosis group, which are considered to have relatively favorable prognosis, BCOR gene mutations appear to be an important prognostic factor.

Full-length mutation search of the TP53 gene in acute myeloid leukemia has increased significance as a prognostic factor.

TP53 gene abnormality has been reported to be an unfavorable prognostic factor in acute myeloid leukemia (AML). However, almost all studies of TP53 gene abnormality so far have been limited to mutation searches in the DNA binding domain. As there have been few reports examining both mutation and deletion over the full-length of the TP53 gene, the clinical characteristics of TP53 gene abnormality have not yet been clearly established. In this study, TP53 gene mutation was observed in 7.3% of the total 412 de novo AML cases (33 mutations in 30 cases), with mutation outside the DNA binding domain in eight cases (27%). TP53 gene deletion was observed in 3.1% of 358 cases. All cases had monoallelic deletion with TP53 gene mutation on the opposite allele. Multivariate analysis demonstrated that TP53 gene mutation in the DNA binding domain and outside the DNA binding domain was an independent poor prognostic factor for overall survival and relapse-free survival among the total cohort and it is also an unfavorable prognostic factor in FLT3-ITD-negative AML cases aged 70 years or below with intermediate cytogenetic prognosis. In stratified treatment, full-length search for TP53 gene mutation is therefore very important.

Imaging findings of solitary uterine granulocytic sarcoma.

A 29-year old woman with a history of vaginal bleeding was referred to our hospital. Transvaginal ultrasonography revealed a hypervascular cervical mass and malignancy was suspected. Computed tomography (CT), magnetic resonance imaging, and 18-F-fluorodeoxyglucose positron emission tomography/CT were performed. She was finally diagnosed with granulocytic sarcoma based on pathological examination.

D816V mutation in the KIT gene activation loop has greater cell-proliferative and anti-apoptotic ability than N822K mutation in core-binding factor acute myeloid leukemia.

In core-binding factor acute myeloid leukemia (CBF-AML), there have been conflicting reports regarding the status as an unfavorable prognostic factor of mutation in the KIT gene, the significance of which remains unclear. We previously reported that prognoses differ between the KIT D816V and N822K mutations. In the present study, we compared in vitro the cell-proliferative and anti-apoptotic ability of D816V and N822K. We transduced these KIT mutations into the interleukin-3-dependent cell line TF-1 (TF-1 KITD816V, TF-1 KITN822K). When these KIT mutations were transduced into TF-1 cells, the cells acquired a proliferative ability independent of growth factor, which was significantly higher in TF-1 KITD816V than in TF-1 KITN822K (p = 0.022). When Ara-C was added in the absence of growth factor, Annexin V assay revealed that TF-1 KITD816V was associated with a significantly lower proportion of apoptotic cells than TF-1 KITN822K (p < 0.001). Regarding signal transduction pathways, both KIT D816V and KIT N822K underwent autophosphorylation in the absence of growth factor. This was followed in KIT D816V by downstream activation of the SRC family kinase pathway in addition to the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway, and in KIT N822K by downstream activation of the mitogen-activated protein kinase (MAPK) pathway in addition to the JAK/STAT pathway. These findings establish that D816V and N822K mutations are situated closely on the KIT receptor activation loop, but D816V has greater cell-proliferative and anti-apoptotic ability than N822K.

Identification of morphogenetic capability limitations via a single starfish embryo/larva reconstruction method.

Reconstruction of a starfish embryo provides unique morphogenesis during the developmental process that is not observed in normal development. Here, we established a novel method for reconstruction from single embryos/larvae. By using this method, we investigated the morphogenetic capabilities in critical steps during the reconstruction process as showed by the reconstructed embryos generated from embryos/larvae at the six developmental stages, or from segregated ectodermal and/or endomesodermal cells. Additionally, the novel method addressed several problems found in prior methods related to reproducibly generating reconstructed embryos. In the reconstructions from the various stage embryos/larvae, the morphogenetic capabilities were substantively reduced in the reconstructed embryos generated from 3-day bipinnaria (3dBp). The combination experiments using ectodermal or endomesodermal cells segregated from 2dBp or 3dBp showed a reduction of the morphogenetic capabilities in both cells types in 3dBp. The reconstructed embryos generated from ectodermal or endomesodermal cells segregated from 2dBp possessed partial morphological features, such as formation of the epithelium or blastopore, but all failed to develop into bipinnariae. These results indicate two limitations of the morphogenetic capabilities during the reconstruction process. Firstly, the morphogenetic capabilities to reconstruct an embryo are considerably reduced between 2dBp and 3dBp. Secondly, cells specified as ectoderm or endomesoderm possess limited morphogenetic capabilities to reconstruct bipinnaria. Furthermore, our results demonstrate that the interaction between these specified cell types is required for reconstruction.