Safety of Intracoronary Human Cord Blood Stem Cells in a Lamb Model of Infant Cardiopulmonary Bypass

Safety and feasibility of adjunct autologous cord blood stem cell therapy during the Norwood heart operation

BACKGROUND

We conducted this phase I, open-label safety and feasibility trial of autologous cord blood (CB) stem cell (CBSC) therapy via a novel blood cardioplegia-based intracoronary infusion technique during the Norwood procedure in neonates with an antenatal diagnosis of hypoplastic left heart syndrome (HLHS). CBSC therapy may support early cardiac remodeling with enhancement of right ventricle (RV) function during the critical interstage period.

METHODS

Clinical grade CB mononucleated cells (CBMNCs) were processed to NetCord-FACT International Standards. To maximize yield, CBSCs were not isolated from CBMNCs. CBMNCs were stored at 4 °C (no cryopreservation) for use within 3 days and delivered after each cardioplegia dose (4 × 15 mL).

RESULTS

Of 16 patients with antenatal diagnosis, 13 were recruited; of these 13 patients, 3 were not treated due to placental abruption (n = 1) or conditions delaying the Norwood for >4 days (n = 2) and 10 received 644.9 ± 134 × 106 CBMNCs, representing 1.5 ± 1.1 × 106 (CD34+) CBSCs. Interstage mortality was 30% (n = 3; on days 7, 25, and 62). None of the 36 serious adverse events (53% linked to 3 deaths) were related to CBMNC therapy. Cardiac magnetic resonance imaging before stage 2 (n = 5) found an RV mass index comparable to that in an exact-matched historical cohort (n = 22), with a mean RV ejection fraction of 66.2 ± 4.5% and mean indexed stroke volume of 47.4 ± 6.2 mL/m2 versus 53.5 ± 11.6% and 37.2 ± 10.3 mL/m2, respectively. All 7 survivors completed stage 2 and are alive with normal RV function (6 with ≤mild and 1 with moderate tricuspid regurgitation).

CONCLUSIONS

This trial demonstrated that autologous CBMNCs delivered in large numbers without prior cryopreservation via a novel intracoronary infusion technique at cardioplegic arrest during Norwood palliation on days 2 to 3 of life is feasible and safe.

Advances in neonatal cell therapies: Proceedings of the First Neonatal Cell Therapies Symposium (2022)

Despite considerable advances, there is a need to improve the outcomes of newborn infants, especially related to prematurity, encephalopathy and other conditions. In principle, cell therapies have the potential to protect, repair, or sometimes regenerate vital tissues; and improve or sustain organ function. In this review, we present highlights from the First Neonatal Cell Therapies Symposium (2022). Cells tested in preclinical and clinical studies include mesenchymal stromal cells from various sources, umbilical cord blood and cord tissue derived cells, and placental tissue and membrane derived cells. Overall, most preclinical studies suggest potential for benefit, but many of the cells tested were not adequately defined, and the optimal cell type, timing, frequency, cell dose or the most effective protocols for the targeted conditions is not known. There is as yet no clinical evidence for benefit, but several early phase clinical trials are now assessing safety in newborn babies. We discuss parental perspectives on their involvement in these trials, and lessons learnt from previous translational work of promising neonatal therapies. Finally, we make a call to the many research groups around the world working in this exciting yet complex field, to work together to make substantial and timely progress to address the knowledge gaps and move the field forward. IMPACT: Survival of preterm and sick newborn infants is improving, but they continue to be at high risk of many systemic and organ-specific complications. Cell therapies show promising results in preclinical models of various neonatal conditions and early phase clinical trials have been completed or underway. Progress on the potential utility of cell therapies for neonatal conditions, parental perspectives and translational aspects are discussed in this paper.

Cell-based therapy to boost right ventricular function and cardiovascular performance in hypoplastic left heart syndrome: Current approaches and future directions

Congenital heart disease remains one of the most frequently diagnosed congenital diseases of the newborn, with hypoplastic left heart syndrome (HLHS) being considered one of the most severe. This univentricular defect was uniformly fatal until the introduction, 40 years ago, of a complex surgical palliation consisting of multiple staged procedures spanning the first 4 years of the child's life. While survival has improved substantially, particularly in experienced centers, ventricular failure requiring heart transplant and a number of associated morbidities remain ongoing clinical challenges for these patients. Cell-based therapies aimed at boosting ventricular performance are under clinical evaluation as a novel intervention to decrease morbidity associated with surgical palliation. In this review, we will examine the current burden of HLHS and current modalities for treatment, discuss various cells therapies as an intervention while delineating challenges and future directions for this therapy for HLHS and other congenital heart diseases.

Safety and efficacy of cell therapies in pediatric heart disease: a systematic review and meta-analysis

BACKGROUND

Adult clinical trials have reported safety and the therapeutic potential of stem cells for cardiac disease. These observations have now translated to the pediatric arena. We conducted a meta-analysis to assess safety and efficacy of cell-based therapies in animal and human studies of pediatric heart disease.

METHODS AND RESULTS

A literature search was conducted to examine the effects of cell-based therapies on: (i) safety and (ii) cardiac function. In total, 18 pre-clinical and 13 human studies were included. Pre-clinical: right ventricular dysfunction was the most common animal model (80%). Cardiac-derived (28%) and umbilical cord blood (24%) cells were delivered intravenously (36%) or intramyocardially (35%). Mortality was similar between cell-based and control groups (OR 0.94; 95% CI 0.05, 17.41). Cell-based treatments preserved ejection fraction by 6.9% (p < 0.01), while intramyocardial at a dose of 1-10 M cells/kg optimized ejection fraction. Clinical: single ventricle physiology was the most common cardiac disease (n = 9). Cardiac tissue was a frequent cell source, dosed from 3.0 × 105 to 2.4 × 107 cells/kg. A decrease in adverse events occurred in the cell-based cohort (OR 0.17, p < 0.01). Administration of cell-based therapies improved ejection fraction (MD 4.84; 95% CI 1.62, 8.07; p < 0.01).

CONCLUSIONS

In this meta-analysis, cell-based therapies were safe and improved specific measures of cardiac function. Implications from this review may provide methodologic recommendations (source, dose, route, timing) for future clinical trials. Of note, many of the results described in this study pattern those seen in adult stem cell reviews and meta-analyses.

Stem cell therapy for preventing neonatal diseases in the 21st century: Current understanding and challenges

Diseases of the preterm newborn such as bronchopulmonary dysplasia, necrotizing enterocolitis, cerebral palsy, and hypoxic-ischemic encephalopathy continue to be major causes of infant mortality and long-term morbidity. Effective therapies for the prevention or treatment for these conditions are still lacking as recent clinical trials have shown modest or no benefit. Stem cell therapy is rapidly emerging as a novel therapeutic tool for several neonatal diseases with encouraging pre-clinical results that hold promise for clinical translation. However, there are a number of unanswered questions and facets to the development of stem cell therapy as a clinical intervention. There is much work to be done to fully elucidate the mechanisms by which stem cell therapy is effective (e.g., anti-inflammatory versus pro-angiogenic), identifying important paracrine mediators, and determining the timing and type of therapy (e.g., cellular versus secretomes), as well as patient characteristics that are ideal. Importantly, the interaction between stem cell therapy and current, standard-of-care interventions is nearly completely unknown. In this review, we will focus predominantly on the use of mesenchymal stromal cells for neonatal diseases, highlighting the promises and challenges in clinical translation towards preventing neonatal diseases in the 21st century.

Autologous stem cell therapy for hypoplastic left heart syndrome: Safety and feasibility of intraoperative intramyocardial injections

OBJECTIVES

Staged surgical palliation for hypoplastic left heart syndrome results in an increased workload on the right ventricle serving as the systemic ventricle. Concerns for cardiac dysfunction and long-term heart failure have generated interest in first-in-infant, cell-based therapies as an additional surgical treatment modality.

METHODS

A phase 1 clinical trial was conducted to evaluate the safety and feasibility of direct intramyocardial injection of autologous umbilical cord blood-derived mononuclear cells in 10 infants with hypoplastic left heart syndrome at the time of stage II palliation.

RESULTS

All 10 patients underwent successful stage II palliation and intramyocardial injection of umbilical cord blood-derived mononuclear cells. Operative mortality was 0%. There was a single adverse event related to cell delivery: An injection site epicardial bleed that required simple oversew. The cohort did not demonstrate any significant safety concerns over 6 months. Additionally, the treatment group did not demonstrate any reduction in cardiac function in the context of the study related intramyocardial injections of autologous cells.

CONCLUSIONS

This phase 1 clinical trial showed that delivering autologous umbilical cord blood-derived mononuclear cells directly into the right ventricular myocardium during planned stage II surgical palliation for hypoplastic left heart syndrome was safe and feasible. Secondary findings of preservation of baseline right ventricular function throughout follow-up and normalized growth rates support the design of a phase 2b follow-up trial.

Intracoronary Stem Cell Delivery to the Right Ventricle: A Preclinical Study

Clinical protocols for stem cell-based therapies are currently under development for patients with hypoplastic left heart syndrome. An ideal cell delivery method should have minimal safety risks and provide a wide distribution of cells to the nonischemic right ventricle (RV). However, the optimal strategy for stem cell delivery to the RV has yet to be explored in a preclinical model, necessary for a hypoplastic left heart syndrome trial. Human c-kit⁺ cardiac stem cells (CSCs) were delivered to healthy Yorkshire swine through the proximal right coronary artery with a stop and reflow technique. The effect of premedication with antiarrhythmic (AA) medications in this model was retrospectively reviewed, with the primary outcome of survival 2 hours after infusion. A group underwent CSC delivery to the RV without prophylactic AA medication (no AA, n = 7), whereas the second group was premedicated with a loading dose and intravenous infusion of amiodarone and lidocaine (AA, n = 13). Cardiac biopsies were obtained from each chamber to ascertain the biodistribution of CSCs. Survival was significantly greater in the prophylactic AA group compared with the group without AA (13/13 [100%] vs 1/7 [14.3%], P < 0.0001). Cardiac arrest during balloon inflation was the cause of death in each of the nonmedicated animals. In the premedicated group, 9 (69.2%) pigs experienced transient ST segment changes in the precordial leads during CSC delivery, which resolved spontaneously. Most c-kit⁺ CSCs were distributed to lateral segments of the RV free wall, consistent with the anatomical course of the right coronary artery (lateral RV, 19.2 ± 1.5 CSCs/field of view vs medial RV, 10.4 ± 1.3 CSCs/field of view, P < 0.0001). Few c-kit⁺ CSCs were identified in the right atrium, septum, or left ventricle. Prophylactic infusion of AA enhances survival in swine undergoing intracoronary delivery of human c-kit⁺ CSCs to the RV. Additionally, intracoronary delivery results in a limited biodistribution of c-kit⁺ CSCs within the RV. Human clinical protocols can be optimized by requiring infusion of AA medications before cell delivery.