骨髓间质干细胞输注对外周血干细胞移植造血恢复的影响

目的:观察骨髓间质干细胞 (MSCs)输注对外周血干细胞移植 (PBSCT)后造血恢复的影响。方法:去脾小鼠经粒细胞集落刺激因子动员后收获外周血单个核细胞 (PBMC)和扩增培养的骨髓间质干细胞 (MSCs),移植给经放 /化疗预处理的BALB/c小鼠,数量分别为10⁶PBMC(PBSCT组)、10⁴MSCs和10⁶ PBMC(实验1组)、10⁶ MSCs和10⁶ PBMC(实验 2组),观察受体鼠 4周的生存率、骨髓有核细胞 (BMNC)、粒细胞巨噬细胞集落形成单位 (CFU-GM)、成纤维细胞集落形成单位 (CFU-F)、外周血白细胞 (WBC)计数等指标。结果:实验 2组的生存率、BMNC、CFU-GM、CFU-F显著高于PBSCT组,WBC计数恢复较PBSCT组快 (P <0.05);实验1组和PBSCT组比较,WBC计算恢复快,CFU-F产率高 (P <0.05)。结论:骨髓间质干细胞输注有促进外周血干细胞移植造血恢复的作用。     

骨髓间充质干细胞对大鼠异基因骨髓移植后移植物抗宿主病的影响

目的：探讨大鼠骨髓间充质干细胞（Mesenchymal stem cells，MSCs）对异基因骨髓移植（allo—BMT）后移植物抗宿主病（GVHD）的影响。方法：从大鼠骨髓中分离培养问充质干细胞，通过形态学观察及流式细胞术检测表面标志以鉴定其纯度。通过混合淋巴细胞培养（MLR）检测MSCs体外对T细胞增殖的影响。建立大鼠GVHD模型（SD—Wistar），对其进行allo—BMT的同时，共移植不同数量供者源性的MSCs，观察受体大鼠的临床表现、绘制Kaplan—Meier生存曲线，并通过病理分析，综合评价MSCs，对allo-BMT后GVHD的影响。结果：在混合淋巴细胞培养体系中加入与反应淋巴细胞同源的MSCs，能够抑制T细胞的增殖，不同MSCs浓度组之问存在显著性差异（P〈0．01）。异基因骨髓移植时，供鼠MSC与T细胞比例为1：5、2：5共输注时，能推迟受鼠GVHD的发生时间，延长生存期，但并未避免GVHD的发生；当比例为1：1时，只有20％的受鼠发生了慢性GVHD反应，1—2周后逐渐缓解，并得到了长期生存，其余80％大鼠均未出现GVHD反应而长期生存。结论：大鼠MSCs不仅在体外能够抑制T细胞的增殖，体内共移植骨髓和高数量的MSCs也可以降低GVHD的发生率和严重程度，并延长受鼠的生存时间。本研究结果为临床GVHD的防治提供了新的思路。     

外周血干细胞动员调节CD34^＋细胞β整合素及L—选择素的表达

目的：观察造血干细胞表面粘附分子的变化在外周血干细胞动员中的作用。方法：用双色免疫荧光法研究15例恶性血液病患者经化疗＋G－CSF动员外击血干细胞前后、骨髓和外周血CD34^ 细胞表面β1整合素（CD49d）、β2整合素（CD11a、CD11b）及L－选择素（CD62L）的表达。结果：①动员后第7天CD34^ 细胞表面较动员前CD49d、CD11a、CD62L表达下降;（P＜0．01）,而CD11b无变化（P＞0．05）。②外周血CD34^ 细胞表达CD49d、CD11a、CD11b、CD62L较骨髓低（P＜0．05）。③外周血CD34^ 细胞绝大多数处于GO／G1期,该期的的干细胞CD49d的密度低于S＋G2／M期。结论：化疗＋G－CSF通过粘附分子的变化而使造血干细胞从骨髓进入外周血中。     

骨髓腔内途径脐血与间质干细胞共移植对造血重建的实验研究

目的：探讨骨髓腔内输注（IBM）脐血与间质干细胞（MSCs）对大鼠造血重建、骨髓MSCs恢复的影响，并研究供体MSCs植入状态以探讨MSCs的作用机制。方法：BrdU标记F344大鼠骨髓MSCs通过双侧胫骨IBM或尾静脉注射（IV）与胎鼠及新生大鼠外周血（FNPB）共移植Wistar雌鼠。监测受鼠存活状况、造血免疫重建、HSCs植入水平及骨髓MSCs恢复情况，并以免疫荧光法检测受鼠骨髓MSCs的来源。结果：(1)2个共移植组60 d存活率均为100%，单纯FNPB移植组仅为66.7%。(2)共移植组的外周血象、骨髓造血干祖细胞集落产率明显高于单纯FNPB移植组，尤以骨髓腔共移植组最佳。(3)2个共移植组的HSCs植入水平无统计学差异，而骨髓腔共移植组明显高于单纯FNPB移植组（P＜0.05）。(4)30 d时各移植组MSCs的增殖能力未达正常水平，但仍以骨髓腔共移植组的恢复情况最佳（P＜0.05）。(5)仅少部分受体可发现供、受体源性MSCs嵌合。 结论：脐血与MSCs共移植可促进受体骨髓MSCs恢复和造血重建，提高HSCs植入率；IBM途径应用安全，促进造血恢复的作用优于IV途径。     

恒河猴骨髓间充质干细胞的体外培养及其端粒酶活性

目的：建立骨髓间充质干细胞(MSCs)的培养方法，并检测其细胞周期及端粒酶活性。方法：无菌抽取恒河猴胫骨骨髓，采用贴壁筛选法分离、培养骨髓MSCs；原位杂交方法检测其端粒酶活性；流式细胞仪检测细胞周期。结果：培养的骨髓MSCs呈梭形，平行排列或成集落；细胞端粒酶活性呈阳性反应；细胞周期中G1、S、G2期的细胞所占百分比分别为89．5％、7．8％、7．7％。结论：培养的骨髓间MSCs处于未分化阶段，具有较强的增殖能力。     

黄芪体外作用对贫血小鼠骨髓基质细胞分泌SCF的影响

目的 研究黄芪注射液（AMI）对贫血小鼠骨髓基质细胞分泌干细胞因子（SCF）的影响。方法 在贫血小鼠骨髓基质细胞培养体系中，分别加入0.1mL不同浓度的AMI（终浓度分别为40mg/L,400mg/L)作为药物1组，药物2组，对照组加入等量的IMDM培养液，检测各实验组培养体系中骨髓成纤维细胞集落（CFU-F）数，同时，分别收集培养上清液，透析浓缩成冻干粉，经IMDM液稀释后作为条件培养液，分别加入到高增殖潜能的集落形成细胞（HPP-CFC）培养体系中，检测各实验组培养上清液中所含SCF的水平。结果 与对照组相比较，药物组的CFU-F数及骨髓基质细胞条件培养液（BMSCM）中SCF的水平均明显升高。结论 一定浓度的AMI可促进贫血小鼠骨髓CFU-F增殖。刺激其骨髓基质细胞分泌SCF。     

猪的脂肪和骨髓来源间充质干细胞培养特性比较

目的明确小型猪的脂肪来源间充质干细胞（A_r_MSCs）和猪的骨髓来源间充质干细胞（BM—MSCsl体外培养特性的异同。方法广西巴马小型猪,雌雄不限,猪龄4～6个月,体质量20～30kg。AT-MSCs来源于小型猪腹股沟皮下组织．BM—MSCs来源于小型猪的骨髓组织。培养AT-MSCs和BM—MSCs并观察它们的细胞形态。流式细胞仪检测Arr_MSCs和BM—MSCs的表面标志物（CD29、CD34、CD45、CD90）。分别观察Arr-MSCs和BM—MSCs的细胞生长分化能力;实时聚合酶链反应（PCR）检测基因表达。结果流式细胞仪检测结果表明,A．r_MSCs和BM—MSCs均表达CD29[分别为（99．06±0．30）％、（99．94±0．05）％]、CD90[分别为（97．404-0．40）％、（97．43±1J29）％1阳性,CD34、CD45阴性。AT-MSCs传代需培养5～7d,而BM—MSCs需培养7～10d。与BM—MSCs比较,AT—MSCs具有更强的生长分化能力。实时PCR检测基因表达结果显示．AT—MSCs和BM—MSCs均能分化心肌特异标志物a—skeletalactin和Troponin—I．二者差异无统计学意义．表明AT—MSCs和BM—MSCs均具备多项分化潜能．结论AT—MSCs是小型猪干细胞移植治疗的理想选择．     

大鼠骨髓间充质干细胞对淋巴细胞增殖影响的体外实验

目的：探讨大鼠骨髓间充质干细胞对淋巴细胞增殖的影响。方法：常规分离培养大鼠的骨髓间充质干细胞（MSCs）及淋巴细胞,灭活后的骨髓间充质干细胞和淋巴细胞混合培养48h后,MTT法检测淋巴细胞的相对细胞数,Hoechst 33258染色观察细胞核变化。结果：MTT结果显示,加入MSCs组OD值明显低于未加MSCs的对照组（p〈0．05）。Hoechst 33258染色显示MSCs组淋巴细胞有核回缩及凋亡小体出现。结论：MSCs对淋巴细胞的增殖有抑制作用,其作用机制可能与细胞凋亡有关。     

不同基因转染对骨髓基质干细胞成骨活性的影响

为了优化骨组织工程种子细胞，探讨不同基因对骨髓基质干细胞（MSCs）成骨活性的影响，我们首先利用RT—PCR方法获得了全长BMP-2．VEGF 165及bFGF基因，克隆入真核表达载体peDNA3．0，鉴定正确后，经脂质体介导转入分离培养的大鼠骨髓基质干细胞，G418筛选出稳定表达株。并利用RT—PCR、免疫组织化学方法证明目的基因能够在骨髓基质干细胞中得到稳定表达。MTT实验结果显示转基因后的MSCs增殖能力有不同程度的提高。细胞内碱性磷酸酶活性明显上调，BMP-2、bFGF转染组骨钙索水平升高，成骨活性增强。提示：BMP-2、bFGF基因修饰的骨髓基质干细胞作为种子细胞能够更为有效地在骨组织工程中发挥作用。     

体外分离培养胎盘多分化潜能细胞的实验研究

目的 探索一种新的获取间充质干细胞（mesemchymal stem cells，MSCs）的来源及方法。MSCs在成人骨髓内含量极低．数量随着年龄的增长而减少。MSCs同时少量出现于外周血以及脐带血、胎儿组织器官内，然而，胎儿组织样本难以获取，脐带血中含量太低。这样，如何获得合适的MSCs来源以建立稳定的培养体系．同时避免伦理道德问题的约束是一个值得探索的课题。方法 消化胎盘实体组织，贴壁培养细胞，观测形态并检测其细胞表面抗原表达以及分化潜能。结果 胎盘组织中分离出的贴壁细胞与骨髓间充质干细胞有相似形态和细胞表面标志，具有分化为成骨细胞以及神经细胞的能力。结论 胎盘组织中含有的多分化潜能细胞（placenta．derived muhipotent cells，PDMCs）与骨髓MSCs形态功能相似．胎盘可以作为获取MSCs的一种有效来源。     

The great migration of bone marrow-derived stem cells toward the ischemic brain: therapeutic implications for stroke and other neurological disorders

Accumulating laboratory studies have implicated the mobilization of bone marrow (BM)-derived stem cells in brain plasticity and stroke therapy. This mobilization of bone cells to the brain is an essential concept in regenerative medicine. Over the past ten years, mounting data have shown the ability of bone marrow-derived stem cells to mobilize from BM to the peripheral blood (PB) and eventually enter the injured brain. This homing action is exemplified in BM stem cell mobilization following ischemic brain injury. Various BM-derived cells, such as hematopoietic stem cells (HSCs), mesenchymal stem cells (MSCs), endothelial progenitor cells (EPCs) and very small embryonic-like cells (VSELs) have been demonstrated to exert therapeutic benefits in stroke. Here, we discuss the current status of these BM-derived stem cells in stroke therapy, with emphasis on possible cellular and molecular mechanisms of action that mediate the cells' beneficial effects in the ischemic brain. When possible, we also discuss the relevance of this therapeutic regimen in other central nervous system (CNS) disorders.     

干细胞生长因子和粒细胞集落刺激因子与心肌梗死大鼠体内骨髓间充质干细胞的迁移

背景：外周静脉移植间充质干细胞只有1%~5%的移植细胞能归巢到心肌梗死区域。 目的：观察干细胞生长因子、粒细胞集落刺激因子对骨髓间充质干细胞归巢的影响。 方法：采用贴壁培养法分离培养SD大鼠骨髓间充质干细胞,取传至3~5代细胞。建立SD大鼠急性心肌梗死模型,干细胞生长因子组、粒细胞集落刺激因子组、干细胞生长因子+粒细胞集落刺激因子组在骨髓间充质干细胞移植前3 d和移植后3 d单独或混合皮下注射干细胞生长因子、粒细胞集落刺激因子,骨髓间充质干细胞组不注射细胞因子。 结果与结论：荧光显微镜下观察,骨髓间充质干细胞迁移至心肌梗死组织,骨髓间充质干细胞组、干细胞生长因子组、粒细胞集落刺激因子组迁移至心肌梗死区的骨髓间充质干细胞数量没有明显的区别(P > 0.05),干细胞生长因子+粒细胞集落刺激因子组的骨髓间充质干细胞数量明显高于其他3组(P < 0.05)。免疫荧光组织化学显示,植入的部分骨髓间充质干细胞表达心肌特异蛋白cTnI。结果说明干细胞生长因子和粒细胞集落刺激因子两种细胞因子联合应用可以促进骨髓间充质干细胞归巢至心肌梗死区域,在体内微环境的诱导下,骨髓间充质干细胞能够转化为心肌样细胞。     

IMT504, the prototype of the immunostimulatory oligonucleotides of the PyNTTTTGT class, increases the number of progenitors of mesenchymal stem cells both in vitro and in vivo: potential use in tissue repair therapy

Bone marrow (BM)-derived adult mesenchymal stem cells (MSCs) have the capacity to differentiate in vitro into different cell lines. This makes them a likely source for application in tissue repair therapies. Here, we report evidence indicating that, both in vivo and in vitro, IMT504, the prototype of the PyNTTTTGT class of immunostimulatory oligonucleotides, significantly increases the number of fibroblast colony-forming units (CFU-Fs) that originate MSCs. When rat BM cells were cultured with IMT504, the mean number of CFU-Fs increased about three times as compared with untreated controls (CFU-F: 19 +/- 6.3 vs. 6.8 +/- 2.0/2 x 10(6) seeded BM cells, p = .03). Furthermore, rats inoculated with IMT504 had a significantly higher number of CFU-Fs both in BM (CFU-F: 124 +/- 33 vs. 38 +/- 17/femur, p = .04) and in peripheral blood (animals with detectable CFU-Fs in circulation 8/12 vs. 2/12, p = .04) as compared with untreated animals. On the other hand, BM-derived adherent cells either treated in vitro with IMT504 or obtained from animals injected with IMT504 possess the capacity to differentiate to the osteogenic and adipogenic cell lineages as regular MSCs. Finally, we found that repair of a bone defect was accelerated in rats injected with IMT504 as compared with control animals (area with consolidated bone: 80% +/- 6.4% vs. 49% +/- 3.5%, p = .03, n = 10 rats per group). Importantly, when two human BM were cultured in the presence of IMT504, the mean number of fibroblastic adherent colonies also increased as compared with controls. These results suggest the possibility of clinical use of IMT504 in bone, and presumably other, tissue repair therapies.     

Orchestration of Chemomobilization and G-CSF Administration for Successful Hematopoietic Stem Cell Collection

Successful collection of peripheral blood stem cells (PBSCs) depends on the optimal orchestration of mobilization chemotherapy, granulocyte colony stimulating factor (G-CSF) application, and CD34⁺ cell number assessment in the peripheral blood (PB). However, determining the optimal timing in accordance to the applied chemomobilization regimen can be challenging. Although most centers apply their own local timing schedules, a reliable timetable including the currently most often used mobilization regimens is lacking. We present a comprehensive analysis of the timing modalities for 11 of the most commonly used chemomobilization regimens. A retrospective analysis was performed on the clinical and PBSC collection parameters (including duration of G-CSF application, time point of CD34⁺ assessment, PB CD34⁺ cell count, number of leukapheresis [LP] sessions, processed blood volume, and CD34⁺ collection results) of 91 representatively selected patients who had undergone stem cell mobilization at 2 collection centers.Six to 10 patients were analyzed per regimen with a variety of diagnoses, including multiple myeloma, malignant lymphoma, and sarcoma. No collection failures (<2?×?10⁶ CD34⁺ cells/kg body weight) were observed. All analyzed patients successfully reached their individual collection goal in adherence to the given schedule of chemotherapy, application of G-CSF, measurement of CD34⁺ cells, and subsequent LP.The presented data on the timing of chemomobilization, G-CSF application, and stem cell collection may be helpful in clinical decision making and contribute to a more transparent and predictable treatment process.     

In vitro control of human bone marrow stromal cells for bone tissue engineering

For the clinical application of cultured human mesenchymal stem cells (MSCs), cells must have minimal contact with fetal calf serum (FCS) because it might be a potential vector for contamination by adventitious agents. The use of human plasma and serum for clinical applications also continues to give rise to considerable concerns with respect to the transmission of known and unknown human infectious agents. With the objective of clinical applications of cultured human MSCs, we tested the ability of autologous plasma, AB human serum, FCS, and artificial serum substitutes containing animal-derived proteins (Ultroser G) or vegetable-derived proteins (Prolifix S6) to permit their growth and differentiation in vitro. To conserve as much autologous plasma as possible, we attempted to mix it at decreasing concentrations with the serum substitute containing vegetable-derived mitogenic factors. Under control conditions, by day 10 all the fibroblast colony-forming units (CFU-Fs) were alkaline phosphatase (ALP) positive. However, their number and size were highly variable among donors. Better CFU-F formation was obtained with Ultroser G, and with human AB serum and autologous plasma mixed at, respectively, 5 and 1% with Prolifix S6. The effects of these mixtures on CFU-F formation demonstrate synergy, with the human serum or plasma supplying the factors that favor differentiation of MSCs while Prolifix S6 supplies the mitogenic factors. Finally, we demonstrated the possibility of controlling human MSC growth and differentiation in vitro. Notably, by means of a minimal quantity of human serum or human plasma mixed with a new serum substitute containing vegetable-derived proteins, we displayed growth and differentiation of human MSCs comparable to that obtained with FCS or serum substitutes containing animal-derived proteins. These results will have crucial significance for future applications of cultured human MSCs in bone tissue engineering.     

Selection of optimal passage of bone marrow-derived mesenchymal stem cells for stem cell therapy in patients with amyotrophic lateral sclerosis

Mesenchymal stem cells (MSCs) obtained from bone marrow (BM) are currently used as an alternative therapy in amyotrophic lateral sclerosis (ALS) patients. Selection of optimal passages of autologous BM-derived MSCs during long-term in vitro expansion is important for clinical trials in patients with ALS. We isolated and expanded MSCs from the BM of eight ALS patients to analyze the growth kinetics, differentiation potential, cellular surface antigen expression, karyotype modifications and secretion of various cytokines during long-term culture. The morphology and size of the cells changed from small and spindle-like cells to large and polygonal types in later passages. The growth rate of the MSCs was highest in the third passage, followed by a gradual decrease. There were no special modifications of cell surface antigens or the karyotype of the MSCs from the first to the tenth passage. MSCs in the fourth passage were differentiated into adipocytes, osteocytes and chondrocytes. When we analyzed the cultured media of MSCs at the third, fifth, seventh and ninth passages, IL-6, VEGF and IL-8 showed high expression, with more than 50 pg/10,000 cells at these passages; however, their expression progressively decreased with additional passages. In addition, secretion of IL-15, GM-CSF, IL-10, PDGF-bb, G-CSF, IL-1β, basic FGF and IFN-γ gradually decreased over prolonged culture. We suggest that MSCs at earlier passages are more suitable for stem cell therapy in ALS patients because of their stability and more potent anti-inflammatory and neuroprotective properties.     

Challenge to Predict Mobilized Peripheral Blood Stem Cells on the Fourth Day of Granulocyte Colony-Stimulating Factor Treatment in Healthy Donors: Predictive Value of Basal CD34+ Cell and Platelet Counts

A longitudinal, prospective, observational, single-center cohort study on healthy donors was designed to identify predictors of CD34⁺ cell mobilization on day 4 after granulocyte colony-stimulating factor (G-CSF) administration. As potential predictors of mobilization, age, sex, body weight, height, blood volume, WBC count, peripheral blood (PB) mononuclear cell count, platelet (Plt) count, and hematocrit and hemoglobin levels were considered. Two different evaluations of CD34⁺ cell counts were determined for each donor: baseline (before G-CSF administration) and in PB on day 4 after G-CSF administration. One hundred twenty-two consecutive healthy donors with a median age of 47.5 years were enrolled. The median value of CD34⁺ on day 4 was 43 cells/µL (interquartile range, 23 to 68), and 81.1% of donors had ≥20 cells/µL. Basal WBC count, Plt count, and CD34⁺ were significantly higher for the subjects with CD34⁺ levels over median values on day 4. A multivariate quartile regression analysis, adjusted by sex, age, basal CD34⁺, and basal Plt count, showed a progressively stronger relationship between baseline CD34⁺ and Plt levels and the CD34⁺ levels on day 4. The basal CD34⁺ cut-off level to predict the levels of CD34⁺ on day 4 was either ≤2 cells/μL or ≥3 cells/μL and that of basal Plt count was ≤229 × 10⁹/L or ≥230 × 10⁹/L, respectively, to determine whether mobilization therapy should or should not be attempted. PB stem cell mobilization with G-CSF was highly effective on day 4, and herein we describe a model for predicting the probability of performing PB stem cell collection after a short course of G-CSF.     

干细胞因子与粒细胞集落刺激因子预处理对大鼠骨髓间质干细胞增殖分化的影响

目的：探讨干细胞因子（SCF）和粒细胞集落刺激因子（G-CSF）促进骨髓间质干细胞（MSCs）增殖及促进其向心肌细胞分化的作用。方法：将SD大鼠随机分成对照组、SCF组、G-CSF组和SCF＋G-CSF联合处理组。流式细胞仪检测第4代MSCs细胞周期。用DAPI（25 mg/L）标记的P4MSCs与心肌细胞共培养。在共培养的第1 d至第5 d用免疫荧光技术分别检测心肌特异性肌节肌球蛋白重链（MHC）、肌钙蛋白T（TnT）的表达，统计向心肌样细胞分化的MSCs百分率。结果：（1）SCF和G-CSF联合应用能明显诱导MSCs进入S期，单因子SCF组和G-CSF组与对照组相比，也明显促进MSCs由G₀/G₁期进入S期（P<0.01）。（2）MSCs与心肌细胞共培养后，SCF和G-CSF联合组MSCs表达心肌特异性蛋白MHC及TnT的阳性百分率均显著高于对照组（P<0.01），单细胞因子组MSCs的心肌特异性蛋白MHC及TnT的阳性表达亦高于对照组（P<0.01）。结论： SCF和G-CSF对MSCs具有促增殖、促分化的作用。     

MSC frequency correlates with blood vessel density in equine adipose tissue

Mesenchymal stem cells (MSCs) are multipotent cells that have the capacity to develop into different mature mesenchymal cell types. They were originally isolated from bone marrow, but MSC-like cells have also been isolated from other tissues. The common feature of all of these tissues is that they all house blood vessels. It is, thus, possible that MSCs are associated with perivascular locations. The objective of this work was to test the hypothesis that MSCs are associated with blood vessels by verifying if MSC frequency positively correlates with blood vessel density. To this end, samples from highly and poorly vascularized adipose tissue sites of two equine donors were collected and processed for histology and cell isolation. MSC frequency in these samples was estimated by means of CFU-F assays, which were performed under MSC conditions. Culture-adherent cells from equine adipose tissue and bone marrow were culture expanded, tested for differentiation into mesenchymal cell types in vitro, and implanted in vivo in porous ceramic vehicles to assess their osteogenic capacity, using human MSCs and brain pericytes as controls. The differentiation assays showed a difference between adipose tissue-derived cells as compared to equine bone marrow MSCs. While differences in CFU-F frequencies between both donors were evident, the CFU-F numbers correlated directly with blood vessel densities (r(2) = 0.86). We consider these preliminary data as further evidence linking MSCs to blood vessels.     

Bone marrow-derived cells contribute to cerulein-induced pancreatic fibrosis in the mouse

Bone marrow (BM) cells may transdifferentiate into circulating fibrocytes and myofibroblasts in organ fibrosis. In this study, we investigated the contribution and functional roles of BM-derived cells in murine cerulein-induced pancreatic fibrosis. C57/BL6 female mice wild-type (WT) or Col 1α1(r/r) male BM transplant, received supraphysiological doses of cerulein to induce pancreatic fibrosis. The CD45(+)Col 1(+) fibrocytes isolated from peripheral blood (PB) and pancreatic tissue were examined by in situ hybridization for Y chromosome detection. The number of BM-derived myofibroblasts, the degree of Sirius red staining and the levels of Col 1α1 mRNA were quantified. The Y chromosome was detected in the nuclei of PB CD45(+)Col 1(+) fibrocytes, confirming that circulating fibrocytes can be derived from BM. Co-expression of α-smooth muscle actin illustrated that fibrocytes can differentiate into myofibroblasts. The number of BM-derived myofibroblasts, degree of collagen deposition and pro-collagen I mRNA expression were higher in the mice that received Col 1α1(r/r) BM, (cells that produce mutated, collagenase-resistant collagen) compared to WT BM, indicating that the genotype of BM cells can alter the degree of pancreatic fibrosis. Our data indicate that CD45(+)Col 1(+) fibrocytes in the PB can be BM-derived, functionally contributing to cerulein-induced pancreatic fibrosis in mice by differentiating into myofibroblasts.