Human Peripheral Blood Mononuclear Cells Incubated in Vasculogenic Conditioning Medium Dramatically Improve Ischemia/Reperfusion Acute Kidney Injury in Mice

Cell therapy in kidney diseases: advancing treatments for renal regeneration

Kidney diseases, including acute kidney injury (AKI) and chronic kidney disease (CKD), pose a significant global health challenge, with high morbidity and mortality rates driven by rising prevalence of risk factors such as diabetes and hypertension. Current therapeutic strategies are often limited, prompting the exploration of advanced cell therapies as potential solutions. This review provides a comprehensive overview of the state of cell therapies in kidney disease, tracing the progression from preclinical studies to clinical applications. Recent studies highlited that cell-based interventions offer kidney-protective properties through mechanisms such as paracrine signaling, immune modulation, and direct tissue integration, demonstrating potential in both AKI and CKD settings. Despite promising results, challenges remain in optimizing cell therapy protocols, including cell sourcing, delivery methods, and long-term outcomes. Finally, the review addresses on efforts to enhance cell function, optimize dosing, and refine delivery techniques to improve clinical outcomes in kidney disease management.

PBMC therapy reduces cell death and tissue fibrosis after acute kidney injury by modulating the pattern of monocyte/macrophage survival in tissue

In this study, we investigated if the therapeutic potential of peripheral blood mononuclear cell (PBMC) therapy in a murine model of ischemic AKI is related with the survival pattern of monocyte/macrophages in tissue. CD-1 mice were subjected to bilateral renal ischemia followed by reperfusion to induce AKI. M2-polarized PBMCs isolated from CD-1 mice were administered intravenously at different time points post-injury. Our results demonstrate that early administration of PBMC therapy attenuates renal tissue damage, reduces tissue cell death and prevents fibrosis development. Reduction of tissue pyroptosis was observed by reduction on NLRP3 inflammasome activation and decreasing IL-1beta and Caspase-1 expression in the kidney. Furthermore, the therapy was shown to mitigate ferroptosis by inducing GPX4 overexpression. Early administration of PBMCs increased the survival pattern of renal tissue-macrophages, promoting a "pro-survival phenotype" resulting in decreased pyroptotic marker NLRP3, IL-1beta and Caspase 1 and increased anti-ferroptotic gene GPX4. Conversely, delayed administration of PBMC therapy exhibits diminished efficacy in preventing cell death and fibrosis in tissue and provoked a decrease in the pro-survival phenotype of both monocyte /macrophages in tissue. Our findings highlight the therapeutic potential of PBMC therapy in mitigating AKI and preventing CKD progression by modulating tissue-resident macrophage survival and reducing their cell death pathways. The fact that the effectiveness of the therapy depends on the time of administration after the injury underscores the importance of early intervention in AKI management.

Body fluid-derived stem cells - an untapped stem cell source in genitourinary regeneration

Somatic stem cells have been obtained from solid organs and tissues, including the bone marrow, placenta, corneal stroma, periosteum, adipose tissue, dental pulp and skeletal muscle. These solid tissue-derived stem cells are often used for tissue repair, disease modelling and new drug development. In the past two decades, stem cells have also been identified in various body fluids, including urine, peripheral blood, umbilical cord blood, amniotic fluid, synovial fluid, breastmilk and menstrual blood. These body fluid-derived stem cells (BFSCs) have stemness properties comparable to those of other adult stem cells and, similarly to tissue-derived stem cells, show cell surface markers, multi-differentiation potential and immunomodulatory effects. However, BFSCs are more easily accessible through non-invasive or minimally invasive approaches than solid tissue-derived stem cells and can be isolated without enzymatic tissue digestion. Additionally, BFSCs have shown good versatility in repairing genitourinary abnormalities in preclinical models through direct differentiation or paracrine mechanisms such as pro-angiogenic, anti-apoptotic, antifibrotic, anti-oxidant and anti-inflammatory effects. However, optimization of protocols is needed to improve the efficacy and safety of BFSC therapy before therapeutic translation.

Therapeutic application of regeneration-associated cells: a novel source of regenerative medicine

Chronic diseases with comorbidities or associated risk factors may impair the function of regenerative cells and the regenerative microenvironment. Following this consideration, the vasculogenic conditioning culture (VCC) method was developed to boost the regenerative microenvironment to achieve regeneration-associated cells (RACs), which contain vasculogenic endothelial progenitor cells (EPCs) and anti-inflammatory/anti-immunity cells. Preclinical and clinical studies demonstrate that RAC transplantation is a safe and convenient cell population for promoting ischemic tissue recovery based on its strong vasculogenicity and functionality. The outputs of the scientific reports reviewed in the present study shed light on the fact that RAC transplantation is efficient in curing various diseases. Here, we compactly highlight the universal features of RACs and the latest progress in their translation toward clinics.

Repetitive administration of cultured human CD34+ cells improve adenine-induced kidney injury in mice

BACKGROUND

There is no established treatment to impede the progression or restore kidney function in human chronic kidney disease (CKD).

AIM

To examine the efficacy of cultured human CD34+ cells with enhanced proliferating potential in kidney injury in mice.

METHODS

Human umbilical cord blood (UCB)-derived CD34+ cells were incubated for one week in vasculogenic conditioning medium. Vasculogenic culture significantly increased the number of CD34+ cells and their ability to form endothelial progenitor cell colony-forming units. Adenine-induced tubulointerstitial injury of the kidney was induced in immunodeficient non-obese diabetic/severe combined immunodeficiency mice, and cultured human UCB-CD34+ cells were administered at a dose of 1 × 10⁶/mouse on days 7, 14, and 21 after the start of adenine diet.

RESULTS

Repetitive administration of cultured UCB-CD34+ cells significantly improved the time-course of kidney dysfunction in the cell therapy group compared with that in the control group. Both interstitial fibrosis and tubular damage were significantly reduced in the cell therapy group compared with those in the control group (P < 0.01). Microvasculature integrity was significantly preserved (P < 0.01) and macrophage infiltration into kidney tissue was dramatically decreased in the cell therapy group compared with those in the control group (P < 0.001).

CONCLUSION

Early intervention using human cultured CD34+ cells significantly improved the progression of tubulointerstitial kidney injury. Repetitive administration of cultured human UCB-CD34+ cells significantly improved tubulointerstitial damage in adenine-induced kidney injury in mice via vasculoprotective and anti-inflammatory effects.

CD34 positive cells as endothelial progenitor cells in biology and medicine

CD34 is a cell surface antigen expressed in numerous stem/progenitor cells including hematopoietic stem cells (HSCs) and endothelial progenitor cells (EPCs), which are known to be rich sources of EPCs. Therefore, regenerative therapy using CD34⁺ cells has attracted interest for application in patients with various vascular, ischemic, and inflammatory diseases. CD34⁺ cells have recently been reported to improve therapeutic angiogenesis in a variety of diseases. Mechanistically, CD34⁺ cells are involved in both direct incorporation into the expanding vasculature and paracrine activity through angiogenesis, anti-inflammatory, immunomodulatory, and anti-apoptosis/fibrosis roles, which support the developing microvasculature. Preclinical, pilot, and clinical trials have well documented a track record of safety, practicality, and validity of CD34⁺ cell therapy in various diseases. However, the clinical application of CD34⁺ cell therapy has triggered scientific debates and controversies in last decade. This review covers all preexisting scientific literature and prepares an overview of the comprehensive biology of CD34⁺ cells as well as the preclinical/clinical details of CD34⁺ cell therapy for regenerative medicine.

Development of Cell Therapies for Renal Disease and Regenerative Medicine

The incidence of renal disease is gradually increasing worldwide, and this condition has become a major public health problem because it is a trigger for many other chronic diseases. Cell therapies using multipotent mesenchymal stromal cells, hematopoietic stem cells, macrophages, and other cell types have been used to induce regeneration and provide a cure for acute and chronic kidney disease in experimental models. This review describes the advances in cell therapy protocols applied to acute and chronic kidney injuries and the attempts to apply these treatments in a clinical setting.

Characterization of Endothelial Progenitor Cell: Past, Present, and Future

Endothelial progenitor cells (EPCs) are currently being studied as candidate cell sources for revascularization strategies. Despite these promising results, widespread clinical acceptance of EPCs for clinical therapies remains hampered by several challenges. The challenges and issues surrounding the use of EPCs and the current paradigm being developed to improve the harvest efficiency and functionality of EPCs for application in regenerative medicine are discussed. It has been observed that controversies have emerged regarding the isolation techniques and classification and origin of EPCs. This manuscript attempts to highlight the concept of EPCs in a sequential manner, from the initial discovery to the present (origin, sources of EPCs, isolation, and identification techniques). Human and murine EPC marker diversity is also discussed. Additionally, this manuscript is aimed at summarizing our current and future prospects regarding the crosstalk of EPCs with the biology of hematopoietic cells and culture techniques in the context of regeneration-associated cells (RACs).

MMP9 secreted from mononuclear cell quality and quantity culture mediates STAT3 phosphorylation and fibroblast migration in wounds

Introduction

Intractable ulcers may ultimately lead to amputation. To promote wound healing, researchers developed a serum-free ex vivo peripheral blood mononuclear cell quality and quantity culture (MNC-QQc) as a source for cell therapy. In mice, pigs, and even humans, cell therapy with MNC-QQc reportedly yields a high regenerative efficacy. However, the mechanism of wound healing by MNC-QQc cells remains largely unknown. Hence, using an in vitro wound healing model, this study aimed to investigate MNC-QQc cells and the migratory potential of dermal fibroblasts.

Methods

After separation from a 50 mL blood sample from healthy individuals, mononuclear cells were cultured for 7 days in a serum-free ex vivo expansion system with five different cytokines (MNC-QQc method). The effects of MNC-QQc cells on human dermal fibroblast migration were observed by scratch assay. An angiogenesis array screened the MNC-QQc cell supernatant for proteins related to wound healing. Finally, fibroblast migration was confirmed by observing the intracellular signal transduction pathways via Western blot.

Results

The migration of fibroblasts co-cultured with MNC-QQc cells increased by matrix metallopeptidase-9 (MMP9) secretion, as suggested by the angiogenesis array. Furthermore, the phosphorylation of signal transducer and activator of transcription 3 (STAT3) in fibroblast/MNC-QQc cell co-culture and fibroblast culture with added recombinant human MMP9 protein increased. When fibroblasts were cultured with either an MMP9 inhibitor or a STAT3 inhibitor, both fibroblast migration and STAT3 phosphorylation were significantly suppressed.

Conclusions

MNC-QQc cells promote wound healing by the secretion of MMP9, which induces fibroblast migration via the STAT3 signaling pathway.

Extracellular Vesicles Derived From Regeneration Associated Cells Preserve Heart Function After Ischemia-Induced Injury

Under vasculogenic conditioning, pro-inflammatory cell subsets of peripheral blood mononuclear cells (PBMCs) shift their phenotype to pro-regenerative cells such as vasculogenic endothelial progenitor cells, M2 macrophages, and regulatory T cells, collectively designated as regeneration-associated cells (RACs). In this study, we evaluated the therapeutic efficacy of RAC-derived extracellular vesicles (RACev) compared to mesenchymal stem cell-derived EVs (MSCev) in the context of myocardial ischemia reperfusion injury (M-IRI). Human PBMCs were cultured with defined growth factors for seven days to harvest RACs. RACev and MSCev were isolated via serial centrifugation and ultracentrifugation. EV quantity and size were characterized by nanoparticle tracking analysis. In vitro, RACev markedly enhanced the viability, and proliferation of human umbilical vein endothelial cells in a dose-dependent manner compared to MSCev. Notably, systemic injection of RACev improved cardiac functions at 4 weeks, such as fractional shortening, and protection from mitral regurgitation than the MSCev-treated group. Histologically, the RACev-transplanted group showed less interstitial fibrosis and enhanced capillary densities compared to the MSCev group. These beneficial effects were coupled with significant expression of angiogenesis, anti-fibrosis, anti-inflammatory, and cardiomyogenesis-related miRs in RACev, while modestly in MSCev. In vivo bioluminescence analysis showed preferential accumulation of RACev in the IR-injured myocardium, while MSCev accumulation was limited. Immune phenotyping analysis confirmed the immunomodulatory effect of MSCev and RACev. Overall, repetitive systemic transplantation of RACev is superior to MSCev in terms of cardiac function enhancements via crucial angiogenesis, anti-fibrosis, anti-inflammation miR delivery to the ischemic tissue.

Acute kidney injury successfully treated with autologous granulocyte colony-stimulating factor-mobilized peripheral blood CD34-positive cell transplantation: A first-in-human report

A 36-year-old man with severe acute kidney injury (AKI) was admitted to Shonan Kamakura General Hospital in Japan. He was diagnosed with refractory hypertension based on a severely elevated blood pressure of 224/116 mmHg and retinal, cardiac, and brain damage revealed by electrocardiogram, fundoscopy, and magnetic resonance imaging, respectively. Although hemodialysis was withdrawn following strict blood pressure control by an angiotensin receptor blocker, severe kidney insufficiency persisted. Therefore, we performed an autologous granulocyte colony-stimulating factor-mobilized peripheral blood CD34-positive cell transplantation. Collected CD34-positive cells were directly infused to both renal arteries. The patient's general condition was unremarkable after intervention, and the serum creatinine level gradually improved to 2.96 mg/dL 23 weeks after cell therapy. Although transient fever and thrombocytosis were observed after intervention, no major adverse events were observed. This patient is the first case in a phase I/II clinical trial of autologous granulocyte colony-stimulating factor-mobilized peripheral blood CD34-positive cell transplantation for severe AKI with a CD34-positive cell dose-escalating protocol (trial number jRCTb030190231).

Quality and quantity culture effectively restores functional and proliferative capacities of endothelial progenitor cell in end-stage renal disease patients

BACKGROUND

Endothelial cell dysfunction plays the crucial role in initiation and propagation of obstructive arteriosclerosis which ultimately causes arterial obstructive syndrome. Additionally, severe endothelial progenitor cells (EPC) dysfunction is always found in those of end-stage renal disease (ESRD) patients. This study tested the hypothesis that a novel method, named "quality and quantity (QQ) culture", could successfully improve the EPC proliferation and function in ESRD patients.

MATERIALS AND METHODS

Peripheral blood mononuclear cells (PBMNCs) were isolated from age-matched control subjects (i.e., normal renal function) (group 1) and ESRD patients (group 2), followed by culture in either conventional EPC culture for one month or in QQ culture for 7 days, respectively. The result showed that as compared to the conventional EPC culture method, the EPC population and M2-like population/ratio (M2/M1) were significantly enriched in QQ culture both in groups 1 and 2 (all p < 0.001), but these parameters did not differ between the groups. As compared with conventional EPC culture, the angiogenesis capacity and colony formation were significantly increased in QQ culture (all p < 0.001), but they showed no difference between groups 1 and 2. In RAW264.7 macrophages treated by liposaccharide, the gene expressions and ELISA findings of pro-inflammatory cytokines (IL-1β/IL-6/TGF-β) and inflammatory mediator (iNOS) were significantly reduced in QQ culture than in conventional EPC culture in groups 1 and 2 (all p < 0.001), but they showed no difference between the groups.

CONCLUSIONS

This study demonstrated that QQ culture enhanced number, proliferation, and angiogenesis of EPCs and anti-inflammatory capacity in ESRD patients.

Ex vivo conditioning of peripheral blood mononuclear cells of diabetic patients promotes vasculogenic wound healing

The quality and quantity of endothelial progenitor cells (EPCs) are impaired in patients with diabetes mellitus patients, leading to reduced tissue repair during autologous EPC therapy. This study aimed to address the limitations of the previously described serum-free Quantity and Quality Control Culture System (QQc) using CD34+ cells by investigating the therapeutic potential of a novel mononuclear cell (MNC)-QQ. MNCs were isolated from 50 mL of peripheral blood of patients with diabetes mellitus and healthy volunteers (n = 13 each) and subjected to QQc for 7 days in serum-free expansion media with VEGF, Flt-3 ligand, TPO, IL-6, and SCF. The vascular regeneration capability of MNC-QQ cells pre- or post-QQc was evaluated with an EPC colony-forming assay, FACS, EPC culture, tube formation assay, and quantitative real time PCR. For in vivo assessment, 1 × 10⁴ pre- and post-MNC-QQc cells from diabetic donors were injected into a murine wound-healing model using Balb/c nude mice. The percentage of wound closure and angio-vasculogenesis was then assessed. This study revealed vasculogenic, anti-inflammatory, and wound-healing effects of MNC-QQ therapy in both in vitro and in vivo models. This system addresses the low efficiency and efficacy of the current naïve MNC therapy for wound-healing in diabetic patients. As this technique requires a simple blood draw, isolation, and peripheral blood MNC suspension culture for only a week, it can be used as a simple and effective outpatient-based vascular and regenerative therapy for patients with diabetes mellitus.

Emerging therapeutic strategies for transplantation-induced acute kidney injury: protecting the organelles and the vascular bed

INTRODUCTION

Renal ischemia-reperfusion injury (IRI) is a significant clinical challenge faced by clinicians in a broad variety of clinical settings such as perioperative and intensive care. Renal IRI induced acute kidney injury (AKI) is a global public health concern associated with high morbidity, mortality, and health-care costs. Areas covered: This paper focuses on the pathophysiology of transplantation-related AKI and recent findings on cellular stress responses at the intersection of 1. The Unfolded protein response; 2. Mitochondrial dysfunction; 3. The benefits of mineralocorticoid receptor antagonists. Lastly, perspectives are offered to the readers. Expert opinion: Renal IRI is caused by a sudden and temporary impairment of blood flow to the organ. Defining the underlying cellular cascades involved in IRI will assist us in the identification of novel interventional targets to attenuate IRI with the potential to improve transplantation outcomes. Targeting mitochondrial function and cellular bioenergetics upstream of cellular damage may offer several advantages compared to targeting downstream inflammatory and fibrosis processes. An improved understanding of the cellular pathophysiological mechanisms leading to kidney injury will hopefully offer improved targeted therapies to prevent and treat the injury in the future.

LncRNA TapSAKI promotes inflammation injury in HK-2 cells and urine derived sepsis-induced kidney injury

Objective

To explore the possible mechanism of lncRNA TapSAKI in urine derived sepsis-induced kidney injury.

Materials and methods

In vivo urine-derived sepsis (US) rat model and in vitro LPS-induced HK-2 cells were established, and TapSAKI, miR-22, PTEN, TLR4 and p-p65 expressions were detected by qRT-PCR and western blot. RNA precipitation and RNA pull-down were performed to confirm the interaction between TapSAKI and miR-22.

Results

TapSAKI was up-regulated, miR-22 was down-regulated, PTEN, TLR4 and p-p65 expressions, and inflammatory factors TNF-α and IL-6 levels were up-regulated in kidney tissue of US rats and LPS-induced HK-2 cells. In addition, TapSAKI interacted with miR-22, and negatively modulate miR-22 expression. We also observed TapSAKI promoted PTEN expression, TLR4/NF-κB pathway related proteins TLR4 and p-p65, and apoptosis protein cleaved-caspase-3 through negatively regulating miR-22. Further experiments proved TapSAKI/miR-22/TLR4/NF-κB pathway could promote HK-2 cell apoptosis. Finally, in vivo experiments showed TapSAKI knockdown negatively regulated miR-22 and positively regulate PTEN, decreased renal function indicators blood urea nitrogen and serum creatinine, and reduced TNF-α and IL-6.

Conclusion

TapSAKI was elevated in urine derived sepsis-induced kidney injury, and promoted HK-2 cell apoptosis and inflammatory response through miR-22/PTEN/TLR4/NF-κB pathway.

Regeneration-associated cells improve recovery from myocardial infarction through enhanced vasculogenesis, anti-inflammation, and cardiomyogenesis

Background

Considering the impaired function of regenerative cells in myocardial infarction (MI) patients with comorbidities and associated risk factors, cell therapy to enhance the regenerative microenvironment was designed using regeneration-associated cells (RACs), including endothelial progenitor cells (EPCs) and anti-inflammatory cells.

Methods

RACs were prepared by quality and quantity control culture of blood mononuclear cells (QQMNCs). Peripheral blood mononuclear cells (PBMNCs) were isolated from Lewis rats and conditioned for 5 days using a medium containing stem cell factors, thrombopoietin, Flt-3 ligand, vascular endothelial growth factor, and interleukin-6 to generate QQMNCs.

Results

A 5.3-fold increase in the definitive colony-forming EPCs and vasculogenic EPCs was observed, in comparison to naïve PBMNCs. QQMNCs were enriched with EPCs (28.9-fold, P<0.0019) and M2 macrophages (160.3-fold, P<0.0002). Genes involved in angiogenesis (angpt1, angpt2, and vegfb), stem/progenitors (c-kit and sca-1), and anti-inflammation (arg-1, erg-2, tgfb, and foxp3) were upregulated in QQMNCs. For in vivo experiments, cells were administered into syngeneic rat models of MI. QQMNC-transplanted group (QQ-Tx) preserved cardiac function and fraction shortening 28 days post-MI in comparison with PBMNCs-transplanted (PB-Tx) (P<0.0001) and Control (P<0.0008) groups. QQ-Tx showed enhanced angiogenesis and reduced interstitial left ventricular fibrosis, along with a decrease in neutrophils and an increase in M2 macrophages in the acute phase of MI. Cell tracing studies revealed that intravenously administered QQMNCs preferentially homed to ischemic tissues via blood circulation. QQ-Tx showed markedly upregulated early cardiac transcriptional cofactors (Nkx2-5, 29.8-fold, and Gata-4, 5.2-fold) as well as c-kit (4.5-fold) while these markers were downregulated in PB-Tx. In QQ-Tx animals, de novo blood vessels formed a “Biological Bypass”, observed macroscopically and microscopically, while PB-Tx and Control-Tx groups showed severe fibrotic adhesion to the surrounding tissues, but no epicardial blood vessels.

Conclusion

QQMNCs conferred potent angiogenic and anti-inflammatory properties to the regenerative microenvironment, enhancing myocardiogenesis and functional recovery of rat MI hearts.