Mesenchymal stem or stromal cells (MSCs) are multipotent cells that play a pivotal role in various phases of lung development and lung homeostasis, and potentially also lung regeneration. MSCs do not only self-renew and differentiate into renew tissues, but also have anti-inflammatory and paracrine properties to reduce damage and to support tissue regeneration, constituting a promising cell-based treatment strategy for the repair of damaged alveolar tissue in emphysema. This review discusses the current state of the art regarding the potential of MSCs for the treatment of emphysema. The optimism regarding this treatment strategy is supported by promising results from animal models. Still, there are considerable challenges before effective stem cell treatment can be realized in emphysema patients. It is difficult to draw definitive conclusions from the available animal studies, as different models, dosage protocols, administration routes, and sources of MSCs have been used with different measures of effectiveness. Moreover, the regrowth potential of differentiated tissues and organs differs between species. Essential questions about MSC engraftment, retention, and survival have not been sufficiently addressed in a systematic manner. Few human studies have investigated MSC treatment for chronic obstructive pulmonary disease, demonstrating short-term safety but no convincing benefits on clinical outcomes. Possible explanations for the lack of beneficial effects on clinical outcomes could be the source (bone marrow), route, dosage, frequency of administration, and delivery (lack of a bioactive scaffold). This review will provide a comprehensive overview of the (pre)clinical studies on MSC effects in emphysema and discuss the current challenges regarding the optimal use of MSCs for cell-based therapies.

Mesenchymal stromal cells (MSCs) may provide crucial support in the regeneration of destructed alveolar tissue (emphysema) in COPD. We hypothesized that lung-derived MSCs (LMSCs) from emphysema patients are hampered in their repair capacity, either intrinsically or due to their interaction with the damaged micro-environment. LMSCs were isolated from lung tissue of controls and severe emphysema patients, and characterized at baseline. Additionally, LMSCs were seeded onto control and emphysematous decellularized lung tissue scaffolds and assessed for deposition of extracellular matrix (ECM). We observed no differences in surface markers, differentiation/proliferation potential and expression of ECM genes between control- and COPD-derived LMSCs. Notably, COPD-derived LMSCs displayed lower expression of FGF10 and HGF mRNA, and HGF and decorin protein. When seeded on control decellularized lung tissue scaffolds, control and COPD-derived LMSCs showed no differences in engraftment, proliferation or survival within 2 weeks, with similar ability to deposit new matrix on the scaffolds. Moreover, LMSC numbers and ability to deposit new matrix was not compromised on emphysematous scaffolds. Collectively, our data show that LMSCs from COPD patients compared to controls show less expression of FGF10 mRNA, HGF mRNA and protein and decorin protein, while other features including the mRNA expression of various ECM molecules are unaffected. Furthermore, COPD-derived LMSCs are capable of engraftment, proliferation and functioning on native lung tissue scaffolds. The damaged, emphysematous micro-environment as such does not hamper the potential of LMSCs. Thus, specific intrinsic deficiencies in growth factor production by diseased LMSCs may contribute to impaired alveolar repair in emphysema.

COPD is characterized by irreversible lung tissue damage. We hypothesized that lung-derived mesenchymal stromal cells (LMSCs) reduce alveolar epithelial damage via paracrine processes, and may thus be suitable for cell-based strategies in COPD. We aimed to assess whether COPD-derived LMSCs display abnormalities. LMSCs were isolated from lung tissue of severe COPD patients and non-COPD controls. Effects of LMSC conditioned-medium (CM) on H2O2-induced, electric field- and scratch-injury were studied in A549 and NCI-H441 epithelial cells. In organoid models, LMSCs were co-cultured with NCI-H441 or primary lung cells. Organoid number, size and expression of alveolar type II markers were assessed. Pre-treatment with LMSC-CM significantly attenuated oxidative stress-induced necrosis and accelerated wound repair in A549. Co-culture with LMSCs supported organoid formation in NCI-H441 and primary epithelial cells, resulting in significantly larger organoids with lower type II-marker positivity in the presence of COPD-derived versus control LMSCs. Similar abnormalities developed in organoids from COPD compared to control-derived lung cells, with significantly larger organoids. Collectively, this indicates that LMSCs’ secretome attenuates alveolar epithelial injury and supports epithelial repair. Additionally, LMSCs promote generation of alveolar organoids, with abnormalities in the supportive effects of COPD-derived LMCS, reflective of impaired regenerative responses of COPD distal lung cells.

Background Chronic obstructive pulmonary disease (COPD) is characterized by irreversible lung tissue damage. Novel regenerative strategies are urgently awaited. Cultured mesenchymal stem/stromal cells (MSCs) have shown promising results in experimental models of COPD, but differences between sources may impact on their potential use in therapeutic strategies in patients. Aim To assess the transcriptome of lung-derived MSCs (LMSCs), bone marrow-derived MSCs (BM-MSC) and adipose-derived MSCs (AD-MSCs) from COPD patients and non-COPD controls. Methods We studied differences in gene expression profiles between the MSC-subtypes, as well as between COPD and control using RNA sequencing (RNA-seq). Results We show that besides heterogeneity between donors, MSCs from different sources have strongly divergent gene signatures. The growth factors FGF10 and HGF were predominantly expressed in LMSCs. MSCs from all sources displayed altered expression profiles in COPD, with most pronounced significantly up- and downregulated genes in MSCs from adipose tissue. Pathway analysis revealed that the most differentially expressed genes in COPD-derived AD-MSCs are involved in extracellular matrix (ECM) binding and expression. In LMSCs, the gene that differed most strongly between COPD and control was CSGALNACT1, an ECM modulating gene. Conclusion Autologous MSCs from COPD patients display abnormalities with respect to their transcriptome, which were surprisingly most profound in MSCs from extrapulmonary sources. LMSCs may be optimally equipped for lung tissue repair because of the expression of specific growth factor genes.

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Background: Chronic obstructive pulmonary disease (COPD) is characterized by irreversible lung tissue damage. Novel regenerative strategies are urgently awaited. Cultured mesenchymal stem/stromal cells (MSCs) have shown promising results in experimental models of COPD, but differences between sources may impact on their potential use in therapeutic strategies in patients. Aim:To assess the transcriptome of lung-derived MSCs (LMSCs), bone marrow-derived MSCs (BM-MSC) and adipose-derived MSCs (AD-MSCs) from COPD patients and non-COPD controls. Methods: We studied differences in gene expression profiles between the MSC-subtypes, as well as between COPD and control using RNA sequencing (RNA-seq). Results: We show that besides heterogeneity between donors, MSCs from different sources have strongly divergent gene signatures. The growth factors FGF10 and HGF were predominantly expressed in LMSCs. MSCs from all sources displayed altered expression profiles in COPD, with most pronounced significantly up- and downregulated genes in MSCs from adipose tissue. Pathway analysis revealed that the most differentially expressed genes in COPD-derived AD-MSCs are involved in extracellular matrix (ECM) binding and expression. In LMSCs, the gene that differed most strongly between COPD and control was CSGALNACT1, an ECM modulating gene. Conclusion:Autologous MSCs from COPD patients display abnormalities with respect to their transcriptome, which were surprisingly most profound in MSCs from extrapulmonary sources. LMSCs may be optimally equipped for lung tissue repair because of the expression of specific growth factor genes.