Participation of suicide gene extracellular vesicles in metastasis prevention.

The incidence of distant metastases is associated with most cancer-related mortalities. Extracellular vesicles (EVs), secreted from tumors and cancer-associated fibroblasts, are involved in the metastatic process mediating their organotropism through their involvement in the pre-metastatic niche formation. We have been developing suicide gene therapy mediated by EVs secreted from mesenchymal stem/ stromal cells, tumor cells, and cancer-associated fibroblasts. Suicide gene EVs conjugated with prodrug are tumor tropic, penetrate tumor cells, and kill them by intracellular conversion of nontoxic prodrug to an efficient anti-cancer drug. Here, we discuss findings regarding the possibility of using suicide gene EVs as a novel therapeutic approach for metastases, via pre-metastatic niche modification. The suicide gene EVs provide a future perspective for metastasis prevention.

Suicide-Gene-Modified Extracellular Vesicles of Human Primary Uveal Melanoma in Future Therapies.

Extracellular vesicles secreted from uveal melanoma (UM) cells are involved in the establishment of the premetastatic niche and display transforming potential for the formation of metastases, preferentially in the liver. In this study, we cultivated human primary UM cells and uveal melanoma-associated fibroblasts in vitro to be transduced by infection with a retrovirus containing the suicide gene-fused yeast cytosine deaminase::uracil phospho-ribosyl transferase (yCD::UPRT). A homogenous population of yCD::UPRT-UM cells with the integrated provirus expressed the gene, and we found it to continuously secrete small extracellular vesicles (sEVs) possessing mRNA of the suicide gene. The yCD::UPRT-UM-sEVs were internalized by tumor cells to the intracellular conversion of the prodrug 5-fluorocytosine (5-FC) to the cytotoxic drug 5-fluorouracil (5-FU). The host range of the yCD::UPRT-UM-sEVs was not limited to UMs only. The yCD::UPRT-UM-sEVs inhibited the growth of the human cutaneous melanoma cell line A375 and uveal melanoma cell line MP38, as well as other primary UMs, to various extents in vitro. The yCD::UPRT-UM-sEVs hold the therapeutic and prophylactic potential to become a therapeutic drug for UM. However, the use of yCD::UPRT-UM-sEVs must first be tested in animal preclinical studies.

Tumor-targeted suicide gene-directed enzyme prodrug therapy mediated by extracellular vesicles.

In this article, we describe the gene-directed enzyme prodrug therapy, also known as the "Trojan Horse" therapy mediated by exosomes - small extracellular vesicles (sEVs) secreted from mesenchymal stem/stromal cells (MSCs) and cancer cells. MSC-EVs possess strong migrating tropism toward tumor sites. EVs derived from tumor cells mimic the parental cells in an invasive metastatic growth trait and the capability to reprogram the recipient cells. The behavior of these EVs when modified with the suicide gene predestinates them to be a drug with guided intracellular action. EVs with therapeutic suicide gene are prepared from cells with integrated retrovirus vector containing its genetic message. These EVs are internalized by tumor cells and the product of the gene converts the non-toxic prodrug into a cytotoxic drug inside the cell causing its suicide. The action of two suicide gene systems are described: the yCD::UPRT-MSC/5-FC system and the HSVTK-MSC-GCV system. Suicide gene EVs either MSCs or tumor cell origin due to their intrinsic targeting capabilities, high modification flexibility, as well as biological barrier permeability represent potential drugs for tumors untreatable with present standard cancer therapies.

Extracellular vesicles derived from dental mesenchymal stem/stromal cells with gemcitabine as a cargo have an inhibitory effect on the growth of pancreatic carcinoma cell lines in vitro.

Extracellular vesicles (EVs) are nowadays a target of interest in cancer therapy as a successful drug delivering tool. Based on their many beneficial biocompatible properties are designed to transport nucleic acids, proteins, various nanomaterials or chemotherapeutics. Extracellular vesicles derived from mesenchymal stem/stromal cells (MSCs) possess their tumor-homing abilities. This inspired us to engineer the MSC's EVs to be packed with chemotherapeutic agents and deliver it as a Trojan horse directly into tumor cells. In our study, human dental pulp MSCs (DP-MSCs) were cultivated with gemcitabine (GCB), which led to its absorption by the cells and subsequent secretion of the drug out into conditioned media in EVs. Concentrated conditioned media containing small EVs (potentially exosomes) significantly inhibited the cell growth of pancreatic carcinoma cell lines in vitro. DP-MSCs were simultaneously engineered to express a suicide gene fused yeast cytosinedeaminase:uracilphosphoribosyltransferase (yCD::UPRT). The product of the suicide gene converts non-toxic prodrug 5-fluorocytosine (5-FC) to highly cytotoxic chemotherapeutic drug 5-fluorouracil (5-FU) in the recipient cancer cells. Conversion of 5-FC to 5-FU had an additional effect on cancer cell's growth inhibition. Our results showed a therapeutic potential for DP-MSC-EVs to be designed for successful delivering of chemotherapeutic drugs, together with prodrug suicide gene therapy system.

Low-Dose-Rate Radiation-Induced Secretion of TGF-ß3 Together with an Activator in Small Extracellular Vesicles Modifies Low-Dose Hyper-Radiosensitivity through ALK1 Binding.

Hyper-radiosensitivity (HRS) is the increased sensitivity to low doses of ionizing radiation observed in most cell lines. We previously demonstrated that HRS is permanently abolished in cells irradiated at a low dose rate (LDR), in a mechanism dependent on transforming growth factor ß3 (TGF-ß3). In this study, we aimed to elucidate the activation and receptor binding of TGF-ß3 in this mechanism. T-47D cells were pretreated with inhibitors of potential receptors and activators of TGF-ß3, along with addition of small extracellular vesicles (sEVs) from LDR primed cells, before their radiosensitivity was assessed by the clonogenic assay. The protein content of sEVs from LDR primed cells was analyzed with mass spectrometry. Our results show that sEVs contain TGF-ß3 regardless of priming status, but only sEVs from LDR primed cells remove HRS in reporter cells. Inhibition of the matrix metalloproteinase (MMP) family prevents removal of HRS, suggesting an MMP-dependent activation of TGF-ß3 in the LDR primed cells. We demonstrate a functional interaction between TGF-ß3 and activin receptor like kinase 1 (ALK1) by showing that TGF-ß3 removes HRS through ALK1 binding, independent of ALK5 and TGF-ßRII. These results are an important contribution to a more comprehensive understanding of the mechanism behind TGF-ß3 mediated removal of HRS.

Gene-Directed Enzyme/Prodrug Therapy of Rat Brain Tumor Mediated by Human Mesenchymal Stem Cell Suicide Gene Extracellular Vesicles In Vitro and In Vivo.

MSC-driven, gene-directed enzyme prodrug therapy (GDEPT) mediated by extracellular vesicles (EV) represents a new paradigm-cell-free GDEPT tumor therapy. In this study, we tested the efficacy of yeast cytosine deaminase::uracilphosphoribosyl transferase (yCD::UPRT-MSC)-exosomes, in the form of conditioned medium (CM) to inhibit the growth of C6 glioblastoma cells both in vitro and in vivo. MSCs isolated from human adipose tissue, umbilical cord, or dental pulp engineered to express the yCD::UPRT gene secreted yCD::UPRT-MSC-exosomes that in the presence of the prodrug 5-fluorocytosine (5-FC), inhibited the growth of rat C6 glioblastoma cells and human primary glioblastoma cells in vitro in a dose-dependent manner. CM from these cells injected repeatedly either intraperitoneally (i.p.) or subcutaneously (s.c.), applied intranasally (i.n.), or infused continuously by an ALZET osmotic pump, inhibited the growth of cerebral C6 glioblastomas in rats. A significant number of rats were cured when CM containing yCD::UPRT-MSC-exosomes conjugated with 5-FC was repeatedly injected i.p. or applied i.n. Cured rats were subsequently resistant to challenges with higher doses of C6 cells. Our data have shown that cell-free GDEPT tumor therapy mediated by the yCD::UPRT-MSC suicide gene EVs for high-grade glioblastomas represents a safer and more practical approach that is worthy of further investigation.

Intracellular prodrug gene therapy for cancer mediated by tumor cell suicide gene exosomes.

Recently, we reported about exosomes possessing messenger RNA (mRNA) of suicide gene secreted from mesenchymal stem/stromal cells (MSCs) engineered to express the suicide gene-fused yeast cytosine deaminase::uracil phosphoribosyltransferase (yCD::UPRT). The yCD::UPRT-MSC exosomes are internalized by tumor cells and intracellularly convert prodrug 5-fluorocytosine (5-FC) to cytotoxic drug 5-fluorouracil (5-FU). Human tumor cells with the potential to metastasize release exosomes involved in the creation of a premetastatic niche at the predicted organs. We found that cancer cells stably transduced with yCD::UPRT gene by retrovirus infection released exosomes acting similarly like yCD::UPRT-MSC exosomes. Different types of tumor cells were transduced with the yCD::UPRT gene. The homogenous cell population of yCD::UPRT-transduced tumor cells expressed the yCD::UPRT suicide gene and secreted continuously exosomes with suicide gene mRNA in their cargo. All tumor cell suicide gene exosomes upon internalization into the recipient tumor cells induced the cell death by intracellular conversion of 5-FC to 5-FU and to 5-FUMP in a dose-dependent manner. Most of tumor cell-derived suicide gene exosomes were tumor tropic, in 5-FC presence they killed tumor cells but did not inhibit the growth of human skin fibroblast as well as DP-MSCs. Tumor cell-derived suicide gene exosomes home to their cells of origin and hold an exciting potential to become innovative specific therapy for tumors and potentially for metastases.

Suicide Gene Therapy Mediated with Exosomes Produced by Mesenchymal Stem/Stromal Cells Stably Transduced with HSV Thymidine Kinase.

Mesenchymal stem/stromal cells (MSCs) prepared from various human tissues were stably transduced with the suicide gene herpes simplex virus thymidine kinase (HSVTK) by means of retrovirus infection. HSVTK-transduced MSCs express the suicide gene and in prodrug ganciclovir (GCV) presence induced cell death by intracellular conversion of GCV to GCV-triphosphate. The homogenous population of HSVTK-MSCs were found to release exosomes having mRNA of the suicide gene in their cargo. The exosomes were easily internalized by the tumor cells and the presence of ganciclovir caused their death in a dose-dependent manner. Efficient tumor cell killing of glioma cell lines and primary human glioblastoma cells mediated by HSVTK-MSC exosomes is reported. Exosomes produced by suicide gene transduced MSCs represent a new class of highly selective tumor cell targeted drug acting intracellular with curative potential.

Prodrug suicide gene therapy for cancer targeted intracellular by mesenchymal stem cell exosomes.

The natural behavior of mesenchymal stem cells (MSCs) and their exosomes in targeting tumors is a promising approach for curative therapy. Human tumor tropic mesenchymal stem cells (MSCs) isolated from various tissues and MSCs engineered to express the yeast cytosine deaminase::uracil phosphoribosyl transferase suicide fusion gene (yCD::UPRT-MSCs) released exosomes in conditional medium (CM). Exosomes from all tissue specific yCD::UPRT-MSCs contained mRNA of the suicide gene in the exosome's cargo. When the CM was applied to tumor cells, the exosomes were internalized by recipient tumor cells and in the presence of the prodrug 5-fluorocytosine (5-FC) effectively triggered dose-dependent tumor cell death by endocytosed exosomes via an intracellular conversion of the prodrug 5-FC to 5-fluorouracil. Exosomes were found to be responsible for the tumor inhibitory activity. The presence of microRNAs in exosomes produced from naive MSCs and from suicide gene transduced MSCs did not differ significantly. MicroRNAs from yCD::UPRT-MSCs were not associated with therapeutic effect. MSC suicide gene exosomes represent a new class of tumor cell targeting drug acting intracellular with curative potential.

Mesenchymal Stem Cell Exosome-Mediated Prodrug Gene Therapy for Cancer.

Exosomes derived from human mesenchymal stem cells (MSCs) engineered to express the suicide gene yeast cytosine deaminase::uracil phosphoribosyl transferase (yCD::UPRT) represent a new therapeutic approach for tumor-targeted innovative therapy. The yCD::UPRT-MSC-exosomes carry mRNA of the suicide gene in their cargo. Upon internalization by tumor cells, the exosomes inhibit the growth of broad types of cancer cells in vitro, in the presence of a prodrug. Here we describe the method leading to the production and testing of these therapeutic exosomes. The described steps include the preparation of replication-deficient retrovirus possessing the yCD::UPRT suicide gene, and the preparation and selection of MSCs transduced with yCD::UPRT suicide gene. We present procedures to obtain exosomes possessing the ability to induce the death of tumor cells. In addition, we highlight methods for the evaluation of the suicide gene activity of yCD::UPRT-MSC-exosomes.

Dental Mesenchymal Stem/Stromal Cells and Their Exosomes.

Stem cells derived from human dental pulp tissue (DP-MSC) differ from the other mesenchymal stem cells prepared from bone marrow or adipose tissue due to their embryonic origin from the neural crest and are of special interest because of their neurotropic character. Furthermore, the therapeutic potential of DP-MSCs is realized through paracrine action of extracellularly released components, for which exosomes play an important role. In this review, we intend to explore the properties of these cells with an emphasis on exosomes. The therapeutic applicability of these cells and exosomes in dental practice, neurodegenerative diseases, and many other difficultly treatable diseases, like myocardial infarction, focal cerebral ischemia, acute lung or brain injury, acute respiratory distress syndrome, acute inflammation, and several others is concisely covered. The use of cellular exosomes as an important diagnostic marker and indicator of targeted cancer therapies is also discussed, while the importance of stem cells from human exfoliated deciduous teeth as a source of evolutionally young cells for future regenerative therapies is stressed. We conclude that exosomes derived from these cells are potent therapeutic tools for regenerative medicine in the near future as clinical administration of DP-MSC-conditioned medium and/or exosomes is safer and more practical than stem cells.

Low-Dose-Rate Irradiation for 1 Hour Induces Protection Against Lethal Radiation Doses but Does Not Affect Life Span of DBA/2 Mice.

Prior findings showed that serum from DBA/2 mice that had been given whole-body irradiation for 1 hour at a low dose rate (LDR) of 30 cGy/h induced protection against radiation in reporter cells by a mechanism depending on transforming growth factor ß3 and inducible nitric oxide synthase activity. In the present study, the effect of the 1 hour of LDR irradiation on the response of the preirradiated mice to a subsequent lethal dose and on the life span is examined. These DBA/2 mice were prime irradiated for 1 hour at 30 cGy/h. Two experiments with 9 and 9.5 Gy challenge doses given 6 weeks after priming showed increased survival in primed mice compared to unprimed mice followed up to 225 and 81 days after challenge irradiation, respectively. There was no overall significant difference in life span between primed and unprimed mice when no challenge irradiation was given. The males seemed to have a slight increase in lifespan after priming while the opposite was seen for the females.

TGF-B3 Dependent Modification of Radiosensitivity in Reporter Cells Exposed to Serum From Whole-Body Low Dose-Rate Irradiated Mice.

Prior findings in vitro of a TGF-ß3 dependent mechanism induced by low dose-rate irradiation and resulting in increased radioresistance and removal of low dose hyper-radiosensitivity (HRS) was tested in an in vivo model. DBA/2 mice were given whole-body irradiation for 1 h at low dose-rates (LDR) of 0.3 or 0.03 Gy/h. Serum was harvested and added to RPMI (4% mouse serum and 6% bovine serum).This medium was transferred to reporter cells (T-47D breast cancer cells or T98G glioblastoma cells). The response to subsequent challenge irradiation of the reporter cells was measured by the colony assay. While serum from unirradiated control mice had no effect on the radiosensitivity in the reporter cells, serum from mice given 0.3 Gy/h or 0.03 Gy/h for 1 h removed HRS and also increased survival in response to doses up to 5 Gy. The effect lasted for at least 15 months after irradiation. TGF-ß3 neutralizer added to the medium containing mouse serum inhibited the effect. Serum from mice given irradiation of 0.3 Gy/h for 1 h and subsequently treated with iNOS inhibitor 1400W did not affect radiosensitivity in reporter cells; neither did serum from the unirradiated progeny of mice given 1h LDR whole-body irradiation.

Mesenchymal stem cells expressing therapeutic genes induce autochthonous prostate tumour regression.

Mesenchymal stem cells (MSC) as vehicles of therapeutic genes represent a unique tool to activate drugs within a neoplastic mass due to their property to home and engraft into tumours. In particular, MSC expressing the cytosine deaminase::uracil phosphoribosyltransferase (CD-MSC) have been previously demonstrated to inhibit growth of subcutaneous prostate cancer xenografts thanks to their ability to convert the non-toxic 5-fluorocytosine into the antineoplastic 5-fluorouracil. Since both the immune system and the tumour microenvironment play a crucial role in directing cancer progression, in order to advance towards clinical applications, we tested the therapeutic potential of this approach on animal models that develop autochthonous prostate cancer and preserve an intact immune system. As cell vectors, we employed adipose-tissue and bone-marrow MSC. CD-MSC toxicity on murine prostate cancer cells and tumour tropism were verified in vitro and ex-vivo before starting the preclinical studies. Magnetic Resonance Imaging was utilised to follow orthotopic tumour progression. We demonstrated that intravenous injections of CD-MSC cells, followed by intraperitoneal administration of 5-fluorocytosine, caused tumour regression in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model, which develops aggressive and spontaneous prostate cancer. These results add new insights to the therapeutic potential of specifically engineered MSC in prostate cancer disease.

Comparison of human mesenchymal stem cells derived from dental pulp, bone marrow, adipose tissue, and umbilical cord tissue by gene expression.

AIMS: Our aims were to characterize human mesenchymal stem cells isolated from various tissues by pluripotent stem cells gene expression profile. METHODS: Four strains of dental pulp stem cells (DP-MSCs) were isolated from dental pulp tissue fragments adhered to plastic tissue culture dishes. Mesenchymal stem cells derived from umbilical cord tissue (UBC-MSCs) were isolated with the same technique. Bone marrow derived mesenchymal stem cells (BM-MSCs) were isolated from nucleated cells of bone marrow obtained by density gradient centrifugation. Human mesenchymal stem cells from adipose tissue (AT-MSCs) were isolated by collagenase digestion. All kinds of MSCs used in this study were cultivated in low glucose DMEM containing 5% or human platelet extract. All stem cell manipulation was performed in GMP conditions. Expression of 15 pluripotent stem cells genes on the level of proteins was measured by Proteome Profiler Human Pluripotent Stem Cell Array. Induction of MSCs to in vitro differentiation to adipocytes, osteoblasts, chondroblasts was achieved by cultivation of cells in appropriate differentiation medium. RESULTS: All MSCs tested were phenotypically similar and of fibroblastoid morphology. DP-MSCs and UBC-MSCs were more proliferative than bone marrow BM-MSCs and AT-MSCs. Protein expression of 15 genes typical for pluripotent stem cells distinguished them into two groups. While the gene expression profiles of BM-MSC, AT-MSCs and UBC-MSCs were similar, DP-MSCS differed in relative gene expression on the level of their products in several genes. CONCLUSIONS: Dental pulp mesenchymal stem cells cultivated in vitro under the same conditions as MSCs from bone marrow, adipose tissue and umbilical cord tissue can be distinguished by pluripotent stem cell gene expression profile.

Complete regression of glioblastoma by mesenchymal stem cells mediated prodrug gene therapy simulating clinical therapeutic scenario.

Suicide gene therapy mediated by mesenchymal stem cells with their ability to engraft into tumors makes these therapeutic stem cells an attractive tool to activate prodrugs directly within the tumor mass. In this study, we evaluated the therapeutic efficacy of human mesenchymal stem cells derived from bone marrow and from adipose tissue, engineered to express the suicide gene cytosine deaminase::uracil phosphoribosyltransferase to treat intracerebral rat C6 glioblastoma in a simulated clinical therapeutic scenario. Intracerebrally grown glioblastoma was treated by resection and subsequently with single or repeated intracerebral inoculations of therapeutic stem cells followed by a continuous intracerebroventricular delivery of 5-fluorocytosine using an osmotic pump. Kaplan-Meier survival curves revealed that surgical resection of the tumor increased the survival time of the resected animals depending on the extent of surgical intervention. However, direct injections of therapeutic stem cells into the brain tissue surrounding the postoperative resection cavity led to a curative outcome in a significant number of treated animals. Moreover, the continuous supply of therapeutic stem cells into the brain with growing glioblastoma by osmotic pumps together with continuous prodrug delivery also proved to be therapeutically efficient. We assume that observed curative therapy of glioblastoma by stem cell-mediated prodrug gene therapy might be caused by the destruction of both tumor cells and the niche where glioblastoma initiating cells reside.

Characterization of mesenchymal stem cells of "no-options" patients with critical limb ischemia treated by autologous bone marrow mononuclear cells.

BACKGROUND: Application of autologous bone marrow mononuclear cells to "no option" patients with advanced critical limb ischemia (CLI) prevented major limb amputation in 73% patients during the 6-month follow-up. We examined which properties of bone marrow stromal cells also known as bone-marrow derived mesenchymal stem cells of responding and non-responding patients are important for amputation-free survival. METHODS AND FINDINGS: Mesenchymal stem cells of 41 patients with CLI unsuitable for revascularisation were isolated from mononuclear bone marrow concentrate used for their treatment. Based on the clinical outcome of the treatment, we divided patients into two groups: responders and non-responders. Biological properties of responders' and non-responders' mesenchymal stem cells were characterized according to their ability to multiply, to differentiate in vitro, quantitative expression of cell surface markers, secretion of 27 cytokines, chemokines and growth factors, and to the relative expression of 15 mesenchymal stem cells important genes. Secretome comparison between responders (n=27) and non-responders (n=14) revealed significantly higher secretion values of IL-4, IL-6 and MIP-1b in the group of responders. The expression of cell markers CD44 and CD90 in mesenchymal stem cells from responders was significantly higher compared to non-responders (p<0.01). The expression of mesenchymal stem cells surface markers that was analyzed in 22 patients did not differ between diabetic (n=13) and non-diabetic (n=9) patient groups. Statistically significant higher expression of E-cadherin and PDX-1/IPF1 genes was found in non-responders, while expression of Snail was higher in responders. CONCLUSIONS: The quality of mesenchymal stem cells shown in the expression of cell surface markers, secreted factors and stem cell genes plays an important role in therapeutic outcome. Paracrine mechanisms are main drivers in the induction of reparatory processes in CLI patients. Differences in mesenchymal stem cells properties are discussed in relation to their involvement in the reparatory process.

Intra-arterial autologous bone marrow cell transplantation in a patient with upper-extremity critical limb ischemia.

Induction of therapeutic angiogenesis by autologous bone marrow mononuclear cell transplantation has been identified as a potential new option in patients with advanced lower-limb ischemia. There is little evidence of the benefit of intra-arterial cell application in upper-limb critical ischemia. We describe a patient with upper-extremity critical limb ischemia with digital gangrene resulting from hypothenar hammer syndrome successfully treated by intra-arterial autologous bone marrow mononuclear cell transplantation.

No difference in intra-arterial and intramuscular delivery of autologous bone marrow cells in patients with advanced critical limb ischemia.

Stem cell therapy has been proposed to be an alternative therapy in patients with critical limb ischemia (CLI), not eligible for endovascular or surgical revascularization. We compared the therapeutic effects of intramuscular (IM) and intra-arterial (IA) delivery of bone marrow cells (BMCs) and investigated the factors associated with therapeutic benefits. Forty-one patients (mean age, 66 ± 10 years; 35 males) with advanced CLI (Rutherford category, 5 and 6) not eligible for revascularization were randomized to treatment with 40 ml BMCs using local IM (n = 21) or selective IA infusion (n = 20). Primary endpoints were limb salvage and wound healing. Secondary endpoints were changes in transcutaneous oxygen pressure (tcpO(2)), quality-of-life questionnaire (EQ5D), ankle-brachial index (ABI), and pain scale (0-10). Patients with limb salvage and wound healing were considered to be responders to BMC therapy. At 6-month follow-up, overall limb salvage was 73% (27/37) and 10 subjects underwent major amputation. Four patients died unrelated to stem cell therapy. There was significant improvement in tcpO(2) (15 ± 10 to 29 ± 13 mmHg, p < 0.001), pain scale (4.4 ± 2.6 to 0.9 ± 1.4, p < 0.001), and EQ5D (51 ± 15 to 70 ± 13, p < 0.001) and a significant decrease in the Rutherford category of CLI (5.0 ± 0.2 to 4.3 ± 1.6, p < 0.01). There were no differences among functional parameters in patients undergoing IM versus IA delivery. Responders (n = 27) were characterized by higher CD34(+) cell counts in the bone marrow concentrate (CD34(+) 29 ± 15×10(6) vs. 17 ± 12×10(6), p < 0.05) despite a similar number of total nucleated cells (4.3 ± 1.4×10(9) vs. 4.1 ± 1.2×10(9), p = 0.66) and by a lower level of C-reactive protein (18 ± 28 vs. 100 ± 96 mg/L, p < 0.05) as well as serum leukocytes (8.3 ± 2.1×10(9)/L vs. 12.3 ± 4.5×10(9)/L, p < 0.05) as compared with nonresponders (10 patients). Both IM and IA delivery of autologous stem cells are effective therapeutic strategies in patients with CLI. A higher concentration of CD34(+) cells and a lower degree of inflammation are associated with better clinical therapeutic responses.