The Effect of Bone Marrow Mononuclear Cells on Lung Regeneration and Apoptosis in a Simple Model of Pulmonary Emphysema

Autologous Infusion of Bone Marrow and Mesenchymal Stromal Cells in Patients with Chronic Obstructive Pulmonary Disease: Phase I Randomized Clinical Trial

Background and Objectives

Chronic obstructive pulmonary disease (COPD) is characterized by the destruction of alveolar walls, chronic inflammation and persistent respiratory symptoms. There is no curative clinical treatment for COPD. In this context, cell-based therapy is a promising therapeutic alternative for COPD. Thus, in this open, controlled and randomized Phase I Clinical Trial, we aimed to assess the safety of the infusion of autologous bone marrow mononuclear cells (BMMC), adipose-derived mesenchymal stromal cells (ADSC) and, especially, the safety of concomitant infusion (co-infusion) of BMMC and ADSC as a new therapeutic alternative for COPD. The rationale for co-infusion of BMMC and ADSC is based on the hypothesis of an additive or synergistic therapeutic effect resulting from this association.

Methods

To achieve the proposed objectives, twenty patients with moderate-to-severe COPD were randomly divided into four groups: control group - patients receiving conventional treatment; BMMC group - patients receiving only BMMC; ADSC group - patients receiving only ADSC, and co-infusion group - patients receiving the concomitant infusion of BMMC and ADSC. Patients were assessed for pulmonary function, biochemical profile, and quality of life over a 12 months follow-up.

Results

No adverse events were detected immediately after the infusion of BMMC, ADSC or co-infusion. In the 12-month follow-up, no causal relationship was established between adverse events and cell therapy procedures. Regarding the efficacy, the BMMC group showed an increase in forced expiratory volume (FEV1) and diffusing capacity for carbon monoxide (DLCO). Co-infusion group showed a DLCO, and gas exchange improvement and a better quality of life.

Conclusion

The results obtained allow us to conclude that cell-based therapy with co-infusion of BMMC and ADSC is a safe procedure and a promising therapeutic for COPD. However, additional studies with a greater number of patients are needed before randomized and controlled Phase III clinical trials can be implemented.

A comparative perspective on lung and gill regeneration

The ability to continuously grow and regenerate the gills throughout life is a remarkable property of fish and amphibians. Considering that gill regeneration was first described over one century ago, it is surprising that the underlying mechanisms of cell and tissue replacement in the gills remain poorly understood. By contrast, the mammalian lung is a largely quiescent organ in adults but is capable of facultative regeneration following injury. In the course of the past decade, it has been recognized that lungs contain a population of stem or progenitor cells with an extensive ability to restore tissue; however, despite recent advances in regenerative biology of the lung, the signaling pathways that underlie regeneration are poorly understood. In this Review, we discuss the common evolutionary and embryological origins shared by gills and mammalian lungs. These are evident in homologies in tissue structure, cell populations, cellular function and genetic pathways. An integration of the literature on gill and lung regeneration in vertebrates is presented using a comparative approach in order to outline the challenges that remain in these areas, and to highlight the importance of using aquatic vertebrates as model organisms. The study of gill regeneration in fish and amphibians, which have a high regenerative potential and for which genetic tools are widely available, represents a unique opportunity to uncover common signaling mechanisms that may be important for regeneration of respiratory organs in all vertebrates. This may lead to new advances in tissue repair following lung disease.

Bone Marrow-derived Mesenchymal Stem Cells and Chronic Allograft Disease in a Bronchiolitis Obliterans Animal Model

INTRODUCTION

Bronchiolitis obliterans (BO) is the most common expression of chronic allograft dysfunction in lung transplantation. Moreover, BO represents the major cause of death in the long-term after this procedure. On the other hand, mesenchymal stem cells have been tested in animal models of BO aiming to interfere in its development. The aim of this experimental study is to explore the role of bone-marrow derived stem cells (BMSCs) as a preventive intervention of BO occurrence.

MATERIALS AND METHODS

This an experimental randomized study. A bronchiolitis obliterans animal model in rats was reproduced: heterotopical tracheal transplant model in lung parenchyma. Five of these animals were used as control group. After setting up the model, individuals were divided in 3 groups of treatment (n=15), in which BMSCs were administered in 3 different time points after the tracheal transplant (tracheal transplantation and BMSCs administration occurred the same day, group G0; after 7 days, group G7; after 14 days, group G14. In addition, within each group, BMSCs were administered through 3 different routes: endotracheally, endovascular and topically in the lung parenchyma). Animals were sacrificed at 21 days. Histology, fluorescence in situ hybridization and immunohistochemistry techniques were performed for identifying stem cells.

RESULTS

Compared to control group, animals receiving BMSCs showed large neovessels in a loose fibrous matrix. Group G7 showed less fibrosis (p<0.033) and edema (p<0.028). Moreover, G7 animals receiving stem cells endotracheally showed no fibrosis (p<0.008). Alveolar-like patches of tissue were observed among all groups (53.4%, 46.7% and 40% in G0, G7 and G14 respectively), consisting of cells expressing both stem and alveolar cells biomarkers.

CONCLUSION

BMSCs modify the course of bronchiolitis obliterans and differentiate into alveolar cells. Endotracheal administration of BMSCs 7 days after the heterotopical tracheal transplant might be considered an effective way to prevent BO in this animal model.

Therapeutic effects of bone marrow-derived mononuclear cells from healthy or silicotic donors on recipient silicosis mice

Background

Administration of bone marrow mononuclear cells (BMMCs) modulates lung inflammation and fibrosis in experimental silicosis. However, no studies have evaluated whether silicosis affects the efficacy of autologous BMMCs treatment. We hypothesized that BMMCs obtained from healthy or silicotic mice may improve lung function, but they might affect the inflammatory and fibrotic processes differently in experimental silicosis.

Methods

C57BL/6 mice were randomly divided into control (C) and silicosis (SIL) groups. Mice in the SIL group were instilled with silica particles intratracheally; the C animals received saline using the same protocol. On day 15, the animals were treated with saline (Sal) or BMMCs (2 × 10⁶ cells) from healthy (BMMC-healthy) and silicotic (BMMC-sil) donors. Lung mechanics were measured, and lungs were collected for histology and molecular biology analysis.

Results

BMMCs obtained from healthy and silicotic donors presented similar percentages of cell populations. ^99mTc-BMMCs tracking revealed preferential migration of cells to the liver, and only a few GFP⁺ BMMCs were observed in lung tissue 24 h after treatment, regardless of donor type. Both the SIL-BMMC-healthy and SIL-BMMC-sil groups showed improvement in lung function, a reduction in the fractional area of granuloma, and a decrease in the number of mononuclear and apoptotic cells in lung parenchyma. In addition, the number of F4/80⁺ macrophages, the levels of interleukin-1 beta and transforming growth factor beta, and collagen fiber content in granuloma were reduced in SIL-BMMC-healthy mice, whereas mRNA expression of MMP-9 and procollagen I and III was reduced in the SIL-BMMC-sil group.

Conclusions

Administration of BMMCs from healthy and silicotic donors reduced lung inflammation and fibrosis, thus improving lung function. In addition, BMMC-healthy exhibited a greater improvement in lung morpho-functional changes in murine model of silicosis.