DEFECTS IN HEMATOPOIETIC DIFFERENTIATION IN NZB AND NZC MICE

Hematopoietic stem cell activity in inbred NZB and NZC mice has been determined by transplantation and endogenous spleen colony assays. Whereas NZB mice show normal colony-forming unit (CFU) activity in the transplantation assay, they show markedly elevated endogenous CFU. NZC mice also show this markedly elevated endogenous CFU activity, but in the transplantation assay show only about 5–10% of normal CFU counts. When NZC stem cells are tested for CFU activity in irradiated recipients of the H-2^d type, almost normal colony numbers occur. NZB stem cells however also cannot form colonies in NZC mice. These results suggest that NZC mice have a defect in the micro-environment of the spleen which renders them incapable of allowing transplanted CFU to form colonies. Genetic analysis of both the NZC defect as a CFU recipient, and the elevated endogenous count in NZB and NZC, shows that both are controlled by single recessive genes which are not linked to either coat color, agouti, H-2 or Ig loci. Of even more relevance is the finding that these hematopoietic abnormalities are not linked to the genes involved in controlling autoantibody formation to red cells in the NZB mice. These mice therefore appear to show two distinct hematopoietic abnormalities, the analysis of which may be of considerable value in understanding the detailed events of hematopoietic stem cell differentiation.     

Characterization of a GSK-3 inhibitor in culture of human cord blood primitive hematopoietic cells

Wnt signaling pathway plays important roles in the biology of stem cells in maintaining their self-renewal property. Glycogen synthase kinase-3 (GSK-3) inhibitors, the Wnt signaling agonists, maintain the pluripotency of embryonic stem cells. We report here that a synthetic GSK-3 inhibitor, 6-bromoindirubin-3′-oxime (BIO), showed opposite effects on the expansion of human primitive hematopoietic cells isolated from umbilical cord blood (UCB). In combination with human c-kit ligand (KL), BIO at low concentration (0.2 μM) enhanced the expansion of UCB CD34⁺ cells, which was BIO structure and exposure time dependent; however, at high concentration (2 μM) it inhibited the expansion of the cells. Furthermore, hematopoietic stem cells (HSCs) were exhausted when the UCB CD34⁺ cells were exposed to 0.2 μM BIO and KL longer than 2 days. In conclusion, the use of BIO in expansion of UCB HSCs remains a significant challenge.     

Apoptotic activity and antitumor efficacy of PEGylated TNF-related apoptosis-inducing ligand (TRAIL) in a Mia Paca-2 cell-xenografted mouse model

The purpose of this study was to demonstrate the apoptotic activity and antitumor effect of PEGylated tumor necrosis factor-related apoptosis-inducing ligand (PEG-TRAIL) in pancreatic carcinoma Mia Paca-2 cells and in Mia Paca-2 cell-xenografted mice. PEG-TRAIL was prepared using mPEG-aldehyde (Mw 5 kDa). The apoptosis induced by PEG-TRAIL in Mia Paca-2 cells and in the tumors of Mia Paca-2 cell-xenografted mice was quantified by FACS analysis and using a TUNEL assay. Mia Paca-2 cell-xenografted BALB/c nu/nu mice were administered intratumoral injections of PEG-TRAIL (50 μg/mouse/injection) every 3 days from day 0 (∼4 weeks after xenografting) to day 15. Tumor volumes were measured every 3 days from day 0 to day 27. PEG-TRAIL displayed obvious apoptotic activity in Mia Paca-2 cells; the FACS signal was shifted to the apoptotic area and the cells exhibited green fluorescence indicating apoptosis in the TUNEL assay. Furthermore, PEG-TRAIL was found to suppress tumors in Mia Paca-2 cell-xenografted mice (tumor volumes: 183.9 ± 134.1 for PEG-TRAIL vs. 1827.3 ± 264.5 mm³ for saline control). In addition, in vivo TUNEL assays of tumor tissues showed that the antitumor effect of PEG-TRAIL was due apoptosis. Our findings provide clear in vivo evidence of the antitumor potential of PEG-TRAIL in a Mia Paca-2 cell-xenografted mouse model based of pancreatic cancer.     

The transplantation of neural stem cells and predictive factors in hematopoietic recovery in irradiated mice.

A number of surprising observations have shown that stem cells, in suitable conditions, have the ability to produce a whole spectrum of cell types, regardless, whether these tissues are derived from the same germ layer or not. This phenomenon is called stem cell plasticity, which means that tissue-specific stem cells are mutually interchangeable. In our experiments, as a model, we used neural stem cells (NSCs) harvested from fetal (E14-15) neocortex and beta-galactosidase positive. In the first experiment we found that on days 12 and 30 after sub-lethal irradiation (LD 8.5 Gy) and (beta-galactosidase(+)) NSCs transplantation all mice survived, just as the group with bone marrow transplantation. Moreover, the bone marrow of mice transplanted NSCs contained the number of CFU-GM colonies with beta-galactosidase(+) cells which was as much as 50% higher. These differences were statistically significant, p<0.001. In the second experiment, we studied kinetics of (beta-galactosidase(+)) NSCs after their transplantation to sub-lethally irradiated mice. Histochemistry of tissues was performed on days 12 and 30 post-transplantation, and beta-galactosidase(+) cells were detected with the help of histochemical examination of removed tissues (lung, liver, spleen, thymus, and skeletal muscle). In tissues removed on day 12 post-transplantation, we found a significantly higher number of beta-galactosidase(+) cells in the spleen and thymus on day 30. While we presumed the presence beta-galactosidase(+) cells in the spleen, as spleen and reticuloendothelial system represent an important retaining system for different cell types, the presence of beta-galactosidase(+) cells in the thymus was rather surprising but very interesting. This indicates a certain mutual and close interconnection of transplanted stem cells and immune system in an adult organism. In the third experiment, we verified the mutual interchange of Sca-1 surface antigen in the bone marrow cells and NSCs before transplantation. Analysis of this antigen showed 24.8% Sca-1 positive cells among the bone marrow cells, while NSCs were Sca-1 negative. Our experiments show that NSCs share hemopoietic identity and may significantly influence the recovery of damaged hematopoiesis but do not have typical superficial markers as HSCs. This result is important for the determination of predictive factors for hemopoiesis recovery, for stem cell plasticity and for their use in the cell therapy.     

Expression and clinical significance of tyrosine phosphatase SHP-2 in colon cancer

Protein-tyrosine phosphatase SHP-2, encoded by gene PTPN11, has been identified as a tumor-promoting factor in several types of leukemia and is hyper-activated by other mechanisms in some solid tumors including gastric cancer, breast cancer, non-small cell lung cancer (NSCLC), etc. But few were reported on the expression and significances of SHP-2 in colon cancer. Here, we detect SHP-2 expression in colon cancer cells, colon cancer-induced by AOM + DSS in mice and 232 human colon cancer specimens, including 58 groups of self-matched adjacent peritumor tissues and normal tissues. We found that compared to the normal colon tissues, SHP-2 significantly decreased in tumor tissues (P < 0.001). The same results were got in colon tumor cells as well as mice colon tumors. And in humans samples, low SHP-2 expression showed a significantly correlation with poor tumor differentiation (P < 0.05), late TNM stage (P = 0.1666) and lymph node metastasis (P < 0.05)     

Neurotrophic factor GDNF promotes survival of salivary stem cells

Stem cell–based regenerative therapy is a promising treatment for head and neck cancer patients that suffer from chronic dry mouth (xerostomia) due to salivary gland injury from radiation therapy. Current xerostomia therapies only provide temporary symptom relief, while permanent restoration of salivary function is not currently feasible. Here, we identified and characterized a stem cell population from adult murine submandibular glands. Of the different cells isolated from the submandibular gland, this specific population, Lin^–CD24⁺c-Kit⁺Sca1⁺, possessed the highest capacity for proliferation, self renewal, and differentiation during serial passage in vitro. Serial transplantations of this stem cell population into the submandibular gland of irradiated mice successfully restored saliva secretion and increased the number of functional acini. Gene-expression analysis revealed that glial cell line–derived neurotrophic factor (Gdnf) is highly expressed in Lin^–CD24⁺c-Kit⁺Sca1⁺ stem cells. Furthermore, GDNF expression was upregulated upon radiation therapy in submandibular glands of both mice and humans. Administration of GDNF improved saliva production and enriched the number of functional acini in submandibular glands of irradiated animals and enhanced salisphere formation in cultured salivary stem cells, but did not accelerate growth of head and neck cancer cells. These data indicate that modulation of the GDNF pathway may have potential therapeutic benefit for management of radiation-induced xerostomia.     

Synergistic Actions of Hematopoietic and Mesenchymal Stem/Progenitor Cells in Vascularizing Bioengineered Tissues

Poor angiogenesis is a major road block for tissue repair. The regeneration of virtually all tissues is limited by angiogenesis, given the diffusion of nutrients, oxygen, and waste products is limited to a few hundred micrometers. We postulated that co-transplantation of hematopoietic and mesenchymal stem/progenitor cells improves angiogenesis of tissue repair and hence the outcome of regeneration. In this study, we tested this hypothesis by using bone as a model whose regeneration is impaired unless it is vascularized. Hematopoietic stem/progenitor cells (HSCs) and mesenchymal stem/progenitor cells (MSCs) were isolated from each of three healthy human bone marrow samples and reconstituted in a porous scaffold. MSCs were seeded in micropores of 3D calcium phosphate (CP) scaffolds, followed by infusion of gel-suspended CD34⁺ hematopoietic cells. Co-transplantation of CD34⁺ HSCs and CD34⁻ MSCs in microporous CP scaffolds subcutaneously in the dorsum of immunocompromized mice yielded vascularized tissue. The average vascular number of co-transplanted CD34⁺ and MSC scaffolds was substantially greater than MSC transplantation alone. Human osteocalcin was expressed in the micropores of CP scaffolds and was significantly increased upon co-transplantation of MSCs and CD34⁺ cells. Human nuclear staining revealed the engraftment of transplanted human cells in vascular endothelium upon co-transplantation of MSCs and CD34⁺ cells. Based on additional in vitro results of endothelial differentiation of CD34⁺ cells by vascular endothelial growth factor (VEGF), we adsorbed VEGF with co-transplanted CD34⁺ and MSCs in the microporous CP scaffolds in vivo, and discovered that vascular number and diameter further increased, likely owing to the promotion of endothelial differentiation of CD34⁺ cells by VEGF. Together, co-transplantation of hematopoietic and mesenchymal stem/progenitor cells may improve the regeneration of vascular dependent tissues such as bone, adipose, muscle and dermal grafts, and may have implications in the regeneration of internal organs.     

Tumor growth suppression by adenovirus-mediated introduction of a cell growth suppressing gene tob in a pancreatic cancer model

TOB (transducer of ErbB-2) is a tumor suppressor that interacts with protein-tyrosine kinase receptors, including ErbB-2. Introduction of the tob gene into NIH3T3 cells results in cell growth suppression. In this study, we evaluated the effect of tob expression in pancreatic cell lines (AsPC-1, BxPC-3, SOJ) and discuss the tumor-suppressing effects of adenoviral vector expressing tob cDNA. We first measured the levels of endogenous tob mRNA being expressed in all pancreatic cancer cell lines. Then, we examined the effect of adenoviral vector containing tob cDNA (Ad-tob vector) on cancer cell lines. The viral vector was expanded with transfection in 293 cells. The titer of the vector was 350 × 10⁶ pfu/ml. These cancer cells were able to be transfected with MOI 20 without adenoviral toxicity. The transfection of Ad-tob vector results in growth suppression of SOJ and AsPC-1 cell lines. The magnitude of the expression of the Ad-tob gene in cancer is correlated to tumor suppressive activity. We prepared pancreatic cancer peritonitis models using a peritoneal injection of AsPC-1 cells. In this model, bloody ascites and multiple tumor nodules were seen at the mesentery after 16 days. AdCAtob (50 × 10⁶ pfu/day) was administered from day 5 to day 9 after 4 days of peritoneal injection of 2 × 10⁶ AsPC-1 cells. Tumor growth suppression occurred 10 days after peritoneal injection of AdCAtob compared with the control group. There were no tumor nodules in the abdomen and no bloody ascites. These results suggest that the peritoneal injection of AdCAtob has potential to suppress the formation of pancreatic cancer peritonitis, and can be applied for chemotherapy-resistant cancer peritonitis.     

Aplastic Anemia Rescued by Exhaustion of Cytokine-secreting CD8+ T Cells in Persistent Infection with Lymphocytic Choriomeningitis Virus

Aplastic anemia may be associated with persistent viral infections that result from failure of the immune system to control virus. To evaluate the effects on hematopoiesis exerted by sustained viral replication in the presence of activated T cells, blood values and bone marrow (BM) function were analyzed in chronic infection with lymphocytic choriomeningitis virus (LCMV) in perforin-deficient (P^0/0) mice. These mice exhibit a vigorous T cell response, but are unable to eliminate the virus. Within 14 d after infection, a progressive pancytopenia developed that eventually was lethal due to agranulocytosis and thrombocytopenia correlating with an increasing loss of morphologically differentiated, pluripotent, and committed progenitors in the BM. This hematopoietic disease caused by a noncytopathic chronic virus infection was prevented by depletion of CD8⁺, but not of CD4⁺, T cells and accelerated by increasing the frequency of LCMV-specific CD8⁺ T cells in T cell receptor (TCR) transgenic (tg) mice. LCMV and CD8⁺ T cells were found only transiently in the BM of infected wild-type mice. In contrast, increased numbers of CD8⁺ T cells and LCMV persisted at high levels in antigen-presenting cells of infected P^0/0 and P^0/0 × TCR tg mice. No cognate interaction between the TCR and hematopoietic progenitors presenting either LCMV-derived or self-antigens on the major histocompatibility complex was found, but damage to hematopoiesis was due to excessive secretion and action of tumor necrosis factor (TNF)/lymphotoxin (LT)-α and interferon (IFN)-γ produced by CD8⁺ T cells. This was studied in double-knockout mice that were genetically deficient in perforin and TNF receptor type 1. Compared with P^0/0 mice, these mice had identical T cell compartments and T cell responses to LCMV, yet they survived LCMV infection and became life-long virus carriers. The numbers of hematopoietic precursors in the BM were increased compared with P^0/0 mice after LCMV infection, although transient blood disease was still noticed. This residual disease activity was found to depend on IFN-γ–producing LCMV-specific T cells and the time point of hematopoietic recovery paralleled disappearance of these virus-specific, IFN-γ–producing CD8⁺ T cells. Thus, in the absence of IFN-γ and/or TNF/LT-α, exhaustion of virus-specific T cells was not hampered.     

Vascular niche promotes hematopoietic multipotent progenitor formation from pluripotent stem cells

Pluripotent stem cells (PSCs) represent an alternative hematopoietic stem cell (HSC) source for treating hematopoietic disease. The limited engraftment of human PSC–derived (hPSC-derived) multipotent progenitor cells (MPP) has hampered the clinical application of these cells and suggests that MPP require additional cues for definitive hematopoiesis. We hypothesized that the presence of a vascular niche that produces Notch ligands jagged-1 (JAG1) and delta-like ligand-4 (DLL4) drives definitive hematopoiesis. We differentiated hes2 human embryonic stem cells (hESC) and Macaca nemestrina–induced PSC (iPSC) line-7 with cytokines in the presence or absence of endothelial cells (ECs) that express JAG1 and DLL4. Cells cocultured with ECs generated substantially more CD34⁺CD45⁺ hematopoietic progenitors compared with cells cocultured without ECs or with ECs lacking JAG1 or DLL4. EC-induced cells exhibited Notch activation and expressed HSC-specific Notch targets RUNX1 and GATA2. EC-induced PSC-MPP engrafted at a markedly higher level in NOD/SCID/IL-2 receptor γ chain–null (NSG) mice compared with cytokine-induced cells, and low-dose chemotherapy-based selection further increased engraftment. Long-term engraftment and the myeloid-to-lymphoid ratio achieved with vascular niche induction were similar to levels achieved for cord blood–derived MPP and up to 20-fold higher than those achieved with hPSC-derived MPP engraftment. Our findings indicate that endothelial Notch ligands promote PSC-definitive hematopoiesis and production of long-term engrafting CD34⁺ cells, suggesting these ligands are critical for HSC emergence.     

The protective effect of propofol on ionizing radiation-induced hematopoietic system damage in mice

The hematopoietic system is highly sensitive to ionizing radiation (IR), and IR can cause injury to hematopoietic stem cells (HSCs); the main reason for this may be elevated reactive oxygen species (ROS) levels. Propofol is an anesthetic drug commonly used in clinical practice. The chemical structure of propofol is similar to that of vitamin E, and propofol has an antioxidant capacity. Therefore, in this work the effect of using propofol to protect against IR-induced hematopoietic system injury is evaluated. The data suggested that when the irradiated mice were treated with 20 mg kg⁻¹ of propofol, the survival rate of lethally irradiated mice increased significantly, furthermore, the radiation-induced decrease of white blood cells (WBCs), red blood cells (RBCs), hemoglobin (HGC) and platelets (PLT) in peripheral blood is improved significantly. In addition, propofol could also increase the irradiated HSC and hematopoietic progenitor cell (HPC) frequencies, improving the self-renewal and differentiation abilities of HSCs and HPCs in irradiated mice. Next the ROS levels in HSCs and HPCs were measured, and the results showed that propofol could effectively decrease the ROS levels in these cells. The underlying ROS-scavenging mechanisms are further explored, and the results show that the Nrf2 pathway plays an important role in propofol''s radiation protective effects, however, propofol can also increase the proliferation of the Nrf2 inhibitor-treated Lineage⁻ cells after exposure to 4 Gy radiation. The data suggest that propofol has a radio-protective effect against IR-induced hematopoietic system damage through reducing cellular ROS in HSCs and HPCs partly through the Nrf2 pathway.

Propofol protects against radiation-induced hematopoietic system damage by reducing cellular ROS, partly through the Nrf2 pathway.     

Inhibition of renin–angiotensin system attenuates periadventitial inflammation and reduces atherosclerotic lesion formation

Recent evidence indicates that renin–angiotensin system (RAS) plays an important role in the pathogenesis of atherosclerosis. It was reported that inhibition of RAS with angiotensin II type 1 receptor blockers (ARBs) or angiotensin converting enzyme inhibitors (ACEIs) is effective in prevention of atherosclerosis. Here, we investigated the effects of an ARB or/and an ACEI on atherosclerosis development and periadventitial inflammation in apolipoprotein E (ApoE)-deficient mice. RT-PCR revealed that major RAS components were expressed in periaortic tissue. Ang II infusion significantly increased accumulation of bone marrow derived cells into both neointima (p < 0.05) and periaortic tissue (p < 0.01). Male ApoE- deficient mice were treated with either vehicle, TA606A (10 mg/kg/day, ARB), imidapril (3 mg/kg/day, ACEI) or TA606A plus imidapril (TA606A 10 mg/kg/day + imidapril 3 mg/kg/day, ARB + ACEI) for 24 weeks starting at 12 weeks of age. ARB, ACEI, and ARB + ACEI significantly reduced atherosclerotic lesion formation in aorta compared with vehicle (p < 0.05), with reduced expression of monocyte chemoattractant protein-1 in periaortic tissues (p < 0.01). Neither blood pressure nor heart rate was changed by the treatments at these lower doses. Imidapril significantly reduced lipid deposition in atheroma and plasminogen activator inhibitor-1 expression in periadventitial tissue (p < 0.05, respectively). Imidapril and combination therapy significantly attenuated macrophage infiltration into the atherosclerotic plaque (p < 0.05, respectively). All treatments reduced macrophage accumulation in the periadventitial tissue 12 weeks after treatment (p < 0.05, respectively). These results suggest that inhibition of renin–angiotensin system attenuates periadventitial inflammation and reduces atherosclerotic lesion formation.     

Is there a “gold” standard treatment for patients with isolated myeloid sarcoma?

Isolated myeloid sarcoma is an extramedullary tumor of immature myeloid cells defined by the absence of leukemia history, myelodisplastic syndrome, or myeloproliferative neoplasma with a negative bone marrow biopsy. Myeloid sarcoma is a very rare condition, and few cases have been reported. We reviewed data of 12 patients with isolated myeloid sarcoma managed at a single center to determine the possible prognostic factors affecting patient survival, such as age, sex, type, localization, and treatment options. Patients were mostly men (n = 8), with a median age of 39 years. Patients were initially treated with chemotherapy (n = 7) or surgery (n = 5). In three patients, hematopoietic stem cell transplantation was performed. During the follow-up period, nine patients died. The median overall survival was 13 months, while event-free survival was 8 months. Regarding initial treatment strategy, no significant difference in overall survival was observed. Both chemotherapy and hematopoietic stem cell transplantation independently improved event-free survival. In addition, patients who received chemotherapy combined with hematopoietic stem cell transplantation had significantly longer event-free survival than those treated with chemotherapy alone. Age < 40 years together with chemotherapy/hematopoietic stem cell transplantation significant affected event-free survival. Based on our results, the treatment of myeloid sarcoma requires a systemic rather than a localized approach with surgery or radiotherapy. While prospective evaluations are needed, chemotherapy with allogenic hematopoietic stem cell transplantation should be considered as the optimal therapy for isolated myeloid sarcoma.     

Spleens of myelofibrosis patients contain malignant hematopoietic stem cells

Cancer stem cell behavior is thought to be largely determined by intrinsic properties and by regulatory signals provided by the microenvironment. Myelofibrosis (MF) is characterized by hematopoiesis occurring not only in the marrow but also in extramedullary sites such as the spleen. In order to study the effects of these different microenvironments on primitive malignant hematopoietic cells, we phenotypically and functionally characterized splenic and peripheral blood (PB) MF CD34⁺ cells from patients with MF. MF spleens contained greater numbers of malignant primitive HPCs than PB. Transplantation of PB MF CD34⁺ cells into immunodeficient (NOD/SCID/IL2Rγ^null) mice resulted in a limited degree of donor cell chimerism and a differentiation program skewed toward myeloid lineages. By contrast, transplanted splenic MF CD34⁺ cells achieved a higher level of chimerism and generated both myeloid and lymphoid cells that contained molecular or cytogenetic abnormalities indicating their malignant nature. Only splenic MF CD34⁺ cells were able to sustain hematopoiesis for prolonged periods (9 months) and were able to engraft secondary recipients. These data document the existence of MF stem cells (MF-SCs) that reside in the spleens of MF patients and demonstrate that these MF-SCs retain a differentiation program identical to that of normal hematopoietic stem cells.     

A simple SCID mouse model for HIV research

The engraftment in SCID mice of human cells susceptible to HIV-1 infection was studied. Repopulation of various tissues by CD4⁺ human cells in transplanted SCID recipients was monitored via FACS, PCR, and immunohistology. Injection into SCID mice resulted in extensive proliferation of CD4⁺ cells in the peritoneal cavity, secondary lymphoid organs and other organs. The SCIDCD4⁺ mouse may provide a simple model system for in vivo research purposes such as HIV-1 infection, anti-HIV drug screening, and vaccine development.     

HPMA copolymer-based combination therapy toxic to both prostate cancer stem/progenitor cells and differentiated cells induces durable anti-tumor effects

Current treatments for prostate cancer are still not satisfactory, often resulting in tumor regrowth and metastasis. One of the main reasons for the ineffective anti-prostate cancer treatments is the failure to deplete cancer stem-like cells (CSCs) — a subset of cancer cells with enhanced tumorigenic capacity. Thus, combination of agents against both CSCs and bulk tumor cells may offer better therapeutic benefits. Several molecules with anti-cancer stem/progenitor cell activities have been under preclinical evaluations. However, their low solubility and nonspecific toxicity limit their clinical translation. Herein, we designed a combination macromolecular therapy containing two drug conjugates: HPMA copolymer–cyclopamine conjugate (P–CYP) preferentially toxic to cancer stem/progenitor cells, and HPMA copolymer–docetaxel conjugate (P–DTX) effective in debulking the tumor mass. Both conjugates were synthesized using RAFT (reversible addition–fragmentation chain transfer) polymerization resulting in narrow molecular weight distribution. The killing effects of the two conjugates against bulk tumor cells and CSCs were evaluated in vitro and in vivo. In PC-3 or RC-92a/hTERT prostate cancer cells, P–CYP preferentially kills and impairs the function of CD133 + prostate cancer stem/progenitor cells; P–DTX was able to kill bulk tumor cells instead of CSCs. In a PC-3 xenograft mice model, combination of P–DTX and P–CYP showed the most effective and persistent tumor growth inhibitory effect. In addition, residual tumors contained less CD133 + cancer cells following combination or P–CYP treatments, indicating selective killing of cancer cells with stem/progenitor cell properties.     

Early recombinant human epidermal growth factor treatment recovers the irradiation-induced decrease of Na+ absorption prior to the definite histological mucositis

Recombinant human epidermal growth factor (rhEGF) has potential benefit for the mucositis induced by radiation therapy as a therapeutic setting. In this study, we aimed to investigate the effects of rhEGF treatment on the radiation-induced changes in epithelial transport function, before the occurrence of the definitive histological mucosal changes. C3H/He mice received 0, 4, or 8 Gy irradiation and/or EGF treatment (rhEGF 0, 1 and 5 mg/kg, i.p., 5 days). At day 7, we recorded short circuit current (I_sc) of the upper tracheal epithelium using the flow-type Ussing chamber method, with histological analysis. As a result, there was no evident pathological change in the epithelium from the irradiated and/or rhEGF treated mice at day 7. The initial level of I_sc and amiloride-sensitive I_sc (ΔI_sc,Amil) were decreased after 8 Gy irradiation, reflecting suppression of basal Na⁺ absorption. The decreased ΔI_sc,Amil was recovered by rhEGF treatment. In conclusion, epithelial Na⁺ channel-dependent basal Na⁺ absorption was primarily affected by irradiation, before the pathological changes. The recovery of basal Na⁺ absorption (ΔI_sc,Amil) suggested a potentially beneficial effect of early rhEGF treatment for irradiation-induced suppression of the upper aerodigestive epithelial functions.