Mapping cellular senescence networks in human diabetic foot ulcers

Cellular senescence, a cell fate defined by irreversible cell cycle arrest, has been observed to contribute to chronic age-related conditions including non-healing wounds, such as diabetic foot ulcers. However, the role of cellular senescence in the pathogenesis of diabetic foot ulcers remains unclear. To examine the contribution of senescent phenotypes to these chronic wounds, differential gene and network analyses were performed on publicly available bulk RNA sequencing of whole skin biopsies of wound edge diabetic foot ulcers and uninvolved diabetic foot skin. Wald tests with Benjamini-Hochberg correction were used to evaluate differential gene expression. Results showed that cellular senescence markers, CDKN1A, CXCL8, IGFBP2, IL1A, MMP10, SERPINE1, and TGFA, were upregulated, while TP53 was downregulated in diabetic foot ulcers compared to uninvolved diabetic foot skin. NetDecoder was then used to identify and compare context-specific protein-protein interaction networks using known cellular senescence markers as pathway sources. The diabetic foot ulcer protein-protein interaction network demonstrated significant perturbations with decreased inhibitory interactions and increased senescence markers compared to uninvolved diabetic foot skin. Indeed, TP53 (p53) and CDKN1A (p21) appeared to be key regulators in diabetic foot ulcer formation. These findings suggest that cellular senescence is an important mediator of diabetic foot ulcer pathogenesis.

Practical management of hypertrophic scarring: the mayo clinic experience

Hypertrophic scarring is a potential consequence of wound healing that causes functional and aesthetic disability. Common treatments include intralesional pharmacotherapy (e.g., triamcinolone), surgical excision, and energy-based laser devices. While numerous treatment methods have been described for hypertrophic scarring, an optimal treatment strategy has yet to be established given variability in clinical presentation. This study aims to identify patient- and provider-preferred treatment patterns. This is a single-center, retrospective study of adult patients that developed post-surgical hypertrophic scarring between 2007 and 2017. Specifically, trends in procedural management for hypertrophic scarring among this cohort were examined. A total of 442 procedures (intralesional steroid injection, surgical excision, laser-based treatment) were identified in 218 patients with a clinical diagnosis of hypertrophic scarring. Approximately 73% were female; 87% were Caucasian. The median age at first procedure was 45.6 years (SD = 17.4). The most frequent anatomical locations for procedures were the trunk (n = 242; 54.8%), followed by head/neck (n = 86; 19.5%), upper extremities (n = 67; 15.2%), and lower extremities (n = 45; 10.2%). Procedural therapies included intralesional steroid injection (n = 221; 50%), surgical excision (n = 112; 25.3%) and laser (fractional non-ablative laser vs. pulsed dye laser; n = 109; 24.5%). Treatment modality varied by stage of treatment, scar anatomical location, and scar size. This single-center series of patients with hypertrophic scarring highlights a patient-centered management approach and offers clinical guidelines for provider-patient shared decision making.

Cellular Senescence in Human Skin Aging: Leveraging Senotherapeutics

BACKGROUND

As the largest organ in the human body, the skin is continuously exposed to intrinsic and extrinsic stimuli that impact its functionality and morphology with aging. Skin aging entails dysregulation of skin cells and loss, fragmentation, or fragility of extracellular matrix fibers that are manifested macroscopically by wrinkling, laxity, and pigmentary abnormalities. Age-related skin changes are the focus of many surgical and nonsurgical treatments aimed at improving overall skin appearance and health.

SUMMARY

As a hallmark of aging, cellular senescence, an essentially irreversible cell cycle arrest with apoptosis resistance and a secretory phenotype, manifests across skin layers by affecting epidermal and dermal cells. Knowledge of skin-specific senescent cells, such as melanocytes (epidermal aging) and fibroblasts (dermal aging), will promote our understanding of age-related skin changes and how to optimize patient outcomes in esthetic procedures.

KEY MESSAGES

This review provides an overview of skin aging in the context of cellular senescence and discusses senolytic intervention strategies to selectively target skin senescent cells that contribute to premature skin aging.

Skin Cancer Associated With Chronic Leg Ulcers in the Population of Olmsted County, Minnesota

Malignant skin tumors in the setting of chronic leg ulcers (CLUs) are often underdiagnosed which may contribute to treatment delay and poor outcomes. The aims of our study were to determine the incidence and clinical characteristics of skin cancers in leg ulcers in the Olmsted County population from 1995 to 2020. We used the Rochester Epidemiology Project (a collaboration between health care providers) infrastructure to describe this epidemiology, allowing "population-based" research. Electronic medical records of adult patients with International Classification of Diseases diagnosis codes for leg ulcers and skin cancers on the legs were queried. Thirty-seven individuals with skin cancers in nonhealing ulcers were identified. The cumulative incidence of skin cancer over the 25-year period was 37:7864 (0.47%). The overall incidence rate was 470 per 100,000 patients. Eleven (29.7%) men and 26 (70.3%) women were identified with mean age of 77 years. History of venous insufficiency was present in 30 (81.1%) patients and diabetes in 13 (35.1%) patients. Clinical characteristics of CLU with skin cancer included abnormal granulation tissue in 36 (94.7%) and irregular borders in 35 (94.6%) cases. Skin cancers among CLUs included 17 (41.5%) basal cell carcinomas, 17 (41.5%) squamous cell carcinomas, 2 (4.9%) melanomas, 2 (4.9%) porocarcinomas, 1 (2.4%) basosquamous cell carcinoma, and 1 (2.4%) eccrine adenocarcinoma. The apparent association between chronic wounds and subsequent biopsy-proven skin cancer of the same site was primarily observed in elderly patients; malignant transformation of wounds favored basal cell carcinoma and squamous cell carcinoma. This retrospective cohort study further characterizes the association between skin cancers and chronic leg wounds.

3D bioprinting-a model for skin aging

Human lifespan continues to extend as an unprecedented number of people reach their seventh and eighth decades of life, unveiling chronic conditions that affect the older adult. Age-related skin conditions include senile purpura, seborrheic keratoses, pemphigus vulgaris, bullous pemphigoid, diabetic foot wounds and skin cancer. Current methods of drug testing prior to clinical trials require the use of pre-clinical animal models, which are often unable to adequately replicate human skin response. Therefore, a reliable model for aged human skin is needed. The current challenges in developing an aged human skin model include the intrinsic variability in skin architecture from person to person. An ideal skin model would incorporate innate functionality such as sensation, vascularization and regeneration. The advent of 3D bioprinting allows us to create human skin equivalent for use as clinical-grade surgical graft, for drug testing and other needs. In this review, we describe the process of human skin aging and outline the steps to create an aged skin model with 3D bioprinting using skin cells (i.e. keratinocytes, fibroblasts and melanocytes). We also provide an overview of current bioprinted skin models, associated limitations and direction for future research.

Cellular senescence in skin-related research: Targeted signaling pathways and naturally occurring therapeutic agents

Despite the growing interest by researchers into cellular senescence, a hallmark of cellular aging, its role in human skin remains equivocal. The skin is the largest and most accessible human organ, reacting to the external and internal environment. Hence, it is an organ of choice to investigate cellular senescence and to target root-cause aging processes using senolytic and senomorphic agents, including naturally occurring plant-based derivatives. This review presents different aspects of skin cellular senescence, from physiology to pathology and signaling pathways. Cellular senescence can have both beneficial and detrimental effects on the skin, indicating that both prosenescent and antisenescent therapies may be desirable, based on the context. Knowledge of molecular mechanisms involved in skin cellular senescence may provide meaningful insights for developing effective therapeutics for senescence-related skin disorders, such as wound healing and cosmetic skin aging changes.

A chronic wound model to investigate skin cellular senescence

Wound healing is an essential physiological process for restoring normal skin structure and function post-injury. The role of cellular senescence, an essentially irreversible cell cycle state in response to damaging stimuli, has emerged as a critical mechanism in wound remodeling. Transiently-induced senescence during tissue remodeling has been shown to be beneficial in the acute wound healing phase. In contrast, persistent senescence, as observed in chronic wounds, contributes to delayed closure. Herein we describe a chronic wound murine model and its cellular senescence profile, including the senescence-associated secretory phenotype.

Diabetic kidney disease induces transcriptome alterations associated with angiogenesis activity in human mesenchymal stromal cells

BACKGROUND

Therapeutic interventions that optimize angiogenic activities may reduce rates of end-stage kidney disease, critical limb ischemia, and lower extremity amputations in individuals with diabetic kidney disease (DKD). Infusion of autologous mesenchymal stromal cells (MSC) is a promising novel therapy to rejuvenate vascular integrity. However, DKD-related factors, including hyperglycemia and uremia, might alter MSC angiogenic repair capacity in an autologous treatment approach.

METHODS

To explore the angiogenic activity of MSC in DKD, the transcriptome of adipose tissue-derived MSC obtained from DKD subjects was compared to age-matched controls without diabetes or kidney impairment. Next-generation RNA sequencing (RNA-seq) was performed on MSC (DKD n = 29; Controls n = 9) to identify differentially expressed (DE; adjusted p < 0.05, |log₂fold change|> 1) messenger RNA (mRNA) and microRNA (miRNA) involved in angiogenesis (GeneCards). Paracrine-mediated angiogenic repair capacity of MSC conditioned medium (MSCcm) was assessed in vitro using human umbilical vein endothelial cells incubated in high glucose and indoxyl sulfate for a hyperglycemic, uremic state.

RESULTS

RNA-seq analyses revealed 133 DE mRNAs (77 upregulated and 56 down-regulated) and 208 DE miRNAs (119 up- and 89 down-regulated) in DKD-MSC versus Control-MSC. Interestingly, miRNA let-7a-5p, which regulates angiogenesis and participates in DKD pathogenesis, interacted with 5 angiogenesis-associated mRNAs (transgelin/TAGLN, thrombospondin 1/THBS1, lysyl oxidase-like 4/LOXL4, collagen 4A1/COL4A1 and collagen 8A1/COL8A1). DKD-MSCcm incubation with injured endothelial cells improved tube formation capacity, enhanced migration, reduced adhesion molecules E-selectin, vascular cell adhesion molecule 1 and intercellular adhesion molecule 1 mRNA expression in endothelial cells. Moreover, angiogenic repair effects did not differ between treatment groups (DKD-MSCcm vs. Control-MSCcm).

CONCLUSIONS

MSC from individuals with DKD show angiogenic transcriptome alterations compared to age-matched controls. However, angiogenic repair potential may be preserved, supporting autologous MSC interventions to treat conditions requiring enhanced angiogenic activities such as DKD, diabetic foot ulcers, and critical limb ischemia.

Exosomes: the latest in regenerative aesthetics

Regenerative aesthetics is a burgeoning field for skin rejuvenation and skin health restoration. Exosomes, or extracellular vesicles, represent a new and minimally invasive addition to the regenerative aesthetic toolbox. These nano-sized vesicles contain bioactive cargo with crucial roles in intercellular communication. Exosome technology, while still in its infancy, is now leveraged in regenerative aesthetic medicine due to its multifaceted role in targeting root causes of skin aging and improving overall tissue homeostasis. The main considerations for practice utilization include variation in exosome purification, isolation, storage, scalability and reproducibility. This review aims at highlighting the current and emerging landscape of exosomes in aesthetic medicine including skin rejuvenation and hair restoration.

Targeting Cellular Senescence for Age-Related Diseases: Path to Clinical Translation

SUMMARY

Beyond the palliative reach of today's medicines, medical therapies of tomorrow aim to treat the root cause of age-related diseases by targeting fundamental aging mechanisms. Pillars of aging include, among others, genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, dysregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. The unitary theory of fundamental aging processes posits that by targeting one fundamental aging process, it may be feasible to impact several or all others given its interdependence. Indeed, pathologic accumulation of senescent cells is implicated in chronic diseases and age-associated morbidities, suggesting that senescent cells are a good target for whole-body aging intervention. Preclinical studies using senolytics, agents that selectively eliminate senescent cells, and senomorphics, agents that inhibit production or release of senescence-associated secretory phenotype factors, show promise in several aging and disease preclinical models. Early clinical trials using a senolytic combination (dasatinib and quercetin), and other senolytics including flavonoid, fisetin, and BCL-xL inhibitors, illustrate the potential of senolytics to alleviate age-related dysfunction and diseases including wound healing. Translation into clinical applications requires parallel clinical trials across institutions to validate senotherapeutics as a vanguard for delaying, preventing, or treating age-related disorders and aesthetic aging.

Efficacy and Tolerability of Topical Platelet Exosomes for Skin Rejuvenation: Six-Week Results

BACKGROUND

Exosomes are regenerative mediators for skin rejuvenation. In the context of aesthetic medicine, platelets are an ideal source for exosomal isolation given their role in skin healing. Human platelet extract (HPE) is an allogeneic exosome product derived from US-sourced, leukocyte-reduced apheresed platelets with consistent purity and potency.

OBJECTIVES

To better characterize the saftey and tolerability of novel human platelet extract (plated) Intensive Repair Serum, (Rion Aesthetics, Rochester, MN) and its maximal effects on skin rejuvenation at 6 weeks.

METHODS

This prospective, single-arm, non-randomized, longitudinal study investigated the safety and efficacy of human platelet extract. Structured sub-analysis evaluated multifactorial improvement in skin health following standardized skin care regimen to determine the maximal effect. Evaluation at baseline and 6-weeks included subject questionnaires and photodocumentation using VISIA-CR Generation 5 3D PRIMOS (Canfield Scientific Inc, Fairfield, NJ).

RESULTS

VISIA-CR imaging yielded quantifiable and statistically significant improvements in overall skin health (named "Skin Health Score" [SHS]), calculated by multiplying the luminosity and color evenness scores and dividing the result by wrinkle area x brown spot area x redness area). A greater score correlated to greater overall skin health and there was a statistically significant mean delta improvement 224.2 ± 112.8 (mean ± SD, p ≤ 0.0001) in SHS at 6-weeks compared to baseline. This correlated to reduction in redness, wrinkles, and melanin production across all cosmetic units (p = 0.005, p=0.0023, p ≤ 0.0001, respectively) and significant improvements in luminosity and color evenness (p ≤ 0.001).

CONCLUSIONS

A topically applied platelet-derived exosome product, human platelet extract, induced normalization to skin health at 4-6 weeks with improved various clinical measures of facial photodamage and cutaneous aging. It is safe, well-tolerated, and well-liked by subjects.

Emerging workforce readiness in regenerative healthcare

The biology of regenerative medicine has steadily matured, providing the foundation for randomized clinical trials and translation into validated applications. Today, the growing regenerative armamentarium is poised to impact disease management, yet a gap in training next-generation healthcare providers, equipped to adopt and deliver regenerative options, has been exposed. This special report highlights a multiyear experience in developing and deploying a comprehensive regenerative curriculum for medical trainees. For academicians and institutions invested in establishing a formalized regenerative medicine syllabus, the Regenerative Medicine and Surgery course provides a patient-focused prototype for next-generation learners, offering a dedicated educational experience that encompasses discovery, development and delivery of regenerative solutions. Built with the vision of an evolving regenerative care model, this transdisciplinary endeavor could serve as an adoptable education portal to advance the readiness of the emergent regenerative healthcare workforce globally.

Platelet-rich plasma for the treatment of lichen sclerosus

Aim:

Evaluate the clinical effectiveness of platelet-rich plasma as a treatment for lichen sclerosus.

Methods:

A systematic review was performed. The electronic databases PubMed, Ovid MEDLINE^®, Web of Science, Cochrane, clinicaltrials.gov were used to identify case studies, case series, prospective uncontrolled, and randomized controlled studies published between 1946 and April 21, 2021. Six prospective uncontrolled studies, one randomized double-blind prospective study, and one case report were included.

Results:

Platelet-rich plasma treatment was subjectively reported to improve quality of life, but objective measures demonstrating treatment efficacy were not observed. In addition, platelet-rich plasma preparation and administration between studies lacked standardization.

Conclusion:

Platelet-rich plasma may be used for symptomatic adjuvant treatment of lichen sclerosus, though additional double-blind controlled studies with standardized platelet-rich plasma protocols are needed to better characterize the efficacy of platelet-rich plasma.

Keloids: a review of therapeutic management

Keloid scar formation arises from a disorganized fibroproliferative collagen response that extends beyond the original wound margins because of excessive production of extracellular matrix (ECM). Despite treatment options for keloid scars including medical and surgical therapies, such as intralesional steroid injection and surgical excision, the recurrence rate remains high. Herein we consolidate recently published narrative reviews, systematic reviews, and meta-analyses to provide an overview of updated treatment recommendations for keloidal scar formation. PubMed search engine was used to access the MEDLINE database to investigate updates regarding keloid incidence and treatment. More than 100 articles were reviewed. Keloid management remains a multimodal approach. There continues to be no gold standard of treatment that provides a consistently low recurrence rate; however, the increasing number of available treatments and synergistic combinations of these treatments (i.e., laser-based devices in combination with intralesional steroids, or 5-fluorouracil (5-FU) in combination with steroid therapy) is showing favorable results. Future studies could target the efficacy of novel treatment modalities (i.e., autologous fat grafting or stem cell-based therapies) for keloid management. This review article provides updated treatment guidelines for keloids and discusses insight into management to assist patient-focused, evidence-based clinical decision making.

Graduate training in T cell immunotherapy and CAR-T cell therapy

The objective was to evaluate the impact of an interdisciplinary graduate level course on students’ knowledge and interests in immunotherapy and CAR-T cell therapy. It was a one week course conducted in November 2018. Students were surveyed before and after the course. The survey included questions regarding background, self-perceived knowledge/confidence in skills, and interests/predicted behaviors. Students were assigned to work in interdisciplinary teams to develop a research proposal. A total of 25 students taking the course for graduate level credit were surveyed. Of these, all 25 (100%) completed the surveys. Students came from variable backgrounds and were at different stages of graduate training. After completion of the course, there was a statistically significant increase in self-perceived knowledge of immunotherapy (mean±standard deviation score of 3.6±0.9 post-course vs 2.6±1.0 pre-course, on a 5 point Likert scale, P&lt;0.001), knowledge of the benchtop research to clinic translational process (3.7±0.8 post-course vs 3.0±0.9 pre-course, P&lt;0.001), confidence in critical reading skills (4.3±0.6 post-course vs 4.0±0.5 pre-course, P=0.008), confidence in immunotherapy focused grant writing skills (3.6±0.9 post-course vs 2.8±1.1 pre-course, P&lt;0.001), interest in working in interdisciplinary teams (4.8±0.4 post-course vs 4.6±0.6 pre-course, P=0.02), and interest in attending immunotherapy educational events (3.5±1.3 post-course vs 3.2±1.3 pre-course, P≤0.05). In conclusion, this course helps trainees to build knowledge and interest in the fields of immunotherapy and CAR-T cell therapy and can potentially serve as a platform for future educational courses in interdisciplinary, translational research.

Regenerative medicine curriculum for next-generation physicians

Regenerative sciences are poised to transform clinical practice. The quest for regenerative solutions has, however, exposed a major gap in current healthcare education. A call for evidence-based adoption has underscored the necessity to establish rigorous regenerative medicine educational programs early in training. Here, we present a patient-centric regenerative medicine curriculum embedded into medical school core learning. Launched as a dedicated portal of new knowledge, learner proficiency was instilled by means of a discovery–translation–application blueprint. Using the “from the patient to the patient” paradigm, student experience recognized unmet patient needs, evolving regenerative technologies, and ensuing patient management solutions. Targeted on the deployment of a regenerative model of care, complementary subject matter included ethics, regulatory affairs, quality control, supply chain, and biobusiness. Completion of learning objectives was monitored by online tests, group teaching, simulated clinical examinations along with longitudinal continuity across medical school training and residency. Success was documented by increased awareness and proficiency in domain-relevant content, as well as specialty identification through practice exposure, research engagement, clinical acumen, and education-driven practice advancement. Early incorporation into mainstream medical education offers a tool to train next-generation healthcare providers equipped to adopt and deliver validated regenerative medicine solutions.

FAK auto-phosphorylation site tyrosine 397 is required for development but dispensable for normal skin homeostasis

Focal adhesion kinase (FAK) is an intensely studied non-receptor tyrosine kinase with roles in cancer and other common human diseases. Despite the large interest in FAK, the in vivo contribution of FAK auto-phosphorylation site tyrosine (Y) 397 to FAK function is incompletely understood. To study FAK Y397 in vivo we analyzed mice with 'non-phosphorylatable' Y-to-phenylalanine (F) and 'phospho-mimicking' Y-to-glutamate (E) mutations in the germline. We found that FAK Y397F mice die early during embryogenesis with abnormal angiogenesis like FAK kinase-dead mice. When Y397 is mutated to a glutamate mice survive beyond mid-gestation like mice where Y397 is lost by deletion of FAK exon 15. In culture, defects in proliferation, invasion and gene expression were more severe with the FAK Y397F than with the FAK Y397E mutation despite the inability of FAK Y397E to bind SRC. Conditional expression of FAK Y397F or Y397E in unchallenged avascular epidermis, however, resulted in no appreciable phenotype. We conclude that FAK Y397 is required for the highly dynamic tissue remodeling during development but dispensable for normal homeostasis of avascular epidermis. In contrast to the Y397F mutation, FAK Y397E retains sufficient biological activity to allow for development beyond mid-gestation.

NUP155 insufficiency recalibrates a pluripotent transcriptome with network remodeling of a cardiogenic signaling module

BACKGROUND

Atrial fibrillation is a cardiac disease driven by numerous idiopathic etiologies. NUP155 is a nuclear pore complex protein that has been identified as a clinical driver of atrial fibrillation, yet the precise mechanism is unknown. The present study employs a systems biology algorithm to identify effects of NUP155 disruption on cardiogenicity in a model of stem cell-derived differentiation.

METHODS

Embryonic stem (ES) cell lines (n = 5) with truncated NUP155 were cultured in parallel with wild type (WT) ES cells (n = 5), and then harvested for RNAseq. Samples were run on an Illumina HiSeq 2000. Reads were analyzed using Strand NGS, Cytoscape, DAVID and Ingenuity Pathways Analysis to deconvolute the NUP155-disrupted transcriptome. Network topological analysis identified key features that controlled framework architecture and functional enrichment.

RESULTS

In NUP155 truncated ES cells, significant expression changes were detected in 326 genes compared to WT. These genes segregated into clusters that enriched for specific gene ontologies. Deconvolution of the collective framework into discrete sub-networks identified a module with the highest score that enriched for Cardiovascular System Development, and revealed NTRK1/TRKA and SRSF2/SC35 as critical hubs within this cardiogenic module.

CONCLUSIONS

The strategy of pluripotent transcriptome deconvolution used in the current study identified a novel association of NUP155 with potential drivers of arrhythmogenic AF. Here, NUP155 regulates cardioplasticity of a sub-network embedded within a larger framework of genome integrity, and exemplifies how transcriptome cardiogenicity in an embryonic stem cell genome is recalibrated by nucleoporin dysfunction.

Myocardial Cobalt Levels Are Elevated in the Setting of Total Hip Arthroplasty

BACKGROUND

Arthroplasty implants commonly contain elemental metal that may undergo wear-related release. Recently, cases of hip implant-associated myocardial injury have been reported. However, we are not aware of any previous study that has systematically measured myocardial metal levels or examined the relationship with total hip arthroplasty (THA).

METHODS

Archives of our institution were queried for autopsies of individuals who had undergone THA between 1990 and 2013. Myocardial tissue samples were analyzed for cobalt (Co) and chromium (Cr) levels with inductively coupled plasma mass spectroscopy. Seventy-five Co/Cr-on-polyethylene THA cases were included (mean age at time of death = 77.4 years; 49% women) as were 73 non-arthroplasty controls matched for age, sex, and history of hypertension and diabetes mellitus.

RESULTS

Significantly higher median myocardial concentrations of Co were observed in individuals with THA compared with controls (0.12 versus 0.06 μg/g, p < 0.0001). The median Co concentration was 69% higher in patients who had undergone THA revision (0.169 μg/g) than in those who underwent primary THA (0.100 μg/g; p = 0.004). In general, higher Co levels were observed in those with multiple replaced joints, although this finding only trended toward significance. Cardiomegaly, interstitial fibrosis, and decreased ejection fraction were observed more frequently in the postmortem samples of patients with implants than in those of controls (p = 0.0002, 0.044, and 0.0039, respectively).

CONCLUSIONS

We believe this to be the first study to quantify metal levels in cardiac tissue in patients with and without joint replacement. The elevated Co levels, in concert with cardiomegaly and increased interstitial fibrosis found during autopsy, in the arthroplasty cohort are novel, important findings. Although Co levels were significantly elevated above those in controls, the majority were below those seen in clinical case reports of death from Co cardiotoxicity associated with metal-on-metal prostheses.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Pharmacological Modulation of Calcium Homeostasis in Familial Dilated Cardiomyopathy: An In Vitro Analysis From an RBM20 Patient-Derived iPSC Model

For inherited cardiomyopathies, abnormal sensitivity to intracellular calcium (Ca(2+) ), incurred from genetic mutations, initiates subsequent molecular events leading to pathological remodeling. Here, we characterized the effect of β-adrenergic stress in familial dilated cardiomyopathy (DCM) using human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) from a patient with RBM20 DCM. Our findings suggest that β-adrenergic stimulation accelerated defective Ca(2+) homeostasis, apoptotic changes, and sarcomeric disarray in familial DCM hiPSC-CMs. Furthermore, pharmacological modulation of abnormal Ca(2+) handling by pretreatment with β-blocker, carvedilol, or Ca(2+) -channel blocker, verapamil, significantly decreased the area under curve, reduced percentage of disorganized cells, and decreased terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)-positive apoptotic loci in familial DCM hiPSC-CMs after β-adrenergic stimulation. These translational data provide patient-based in vitro analysis of β-adrenergic stress in RBM20-deficient familial DCM hiPSC-CMs and evaluation of therapeutic interventions to modify heart disease progression, which may be personalized, but more importantly generalized in the clinic.

Systems-based technologies in profiling the stem cell molecular framework for cardioregenerative medicine

Over the last decade, advancements in stem cell biology have yielded a variety of sources for stem cell-based cardiovascular investigation. Stem cell behavior, whether to maintain its stable state of pluripotency or to prime toward the cardiovascular lineage is governed by a set of coordinated interactions between epigenetic, transcriptional, and translational mechanisms. The science of incorporating genes (genomics), RNA (transcriptomics), proteins (proteomics), and metabolites (metabolomics) data in a specific biological sample is known as systems biology. Integrating systems biology in progression with stem cell biologics can contribute to our knowledge of mechanisms that underlie pluripotency maintenance and guarantee fidelity of cardiac lineage specification. This review provides a brief summarization of OMICS-based strategies including transcriptomics, proteomics, and metabolomics used to understand stem cell fate and to outline molecular processes involved in heart development. Additionally, current efforts in cardioregeneration based on the "one-size-fits-all" principle limit the potential of individualized therapy in regenerative medicine. Here, we summarize recent studies that introduced systems biology into cardiovascular clinical outcomes analysis, allowing for predictive assessment for disease recurrence and patient-specific therapeutic response.

Is Local Infiltration Analgesia Superior to Peripheral Nerve Blockade for Pain Management After THA: A Network Meta-analysis

BACKGROUND

Local infiltration analgesia and peripheral nerve blocks are common methods for pain management in patients after THA but direct head-to-head, randomized controlled trials (RCTs) have not been performed. A network meta-analysis allows indirect comparison of individual treatments relative to a common comparator; in this case placebo (or no intervention), epidural analgesia, and intrathecal morphine, yielding an estimate of comparative efficacy.

QUESTIONS/PURPOSES

We asked, when compared with a placebo, (1) does use of local infiltration analgesia reduce patient pain scores and opioid consumption, (2) does use of peripheral nerve blocks reduce patient pain scores and opioid consumption, and (3) is local infiltration analgesia favored over peripheral nerve blocks for postoperative pain management after THA?

METHODS

We searched six databases, from inception through June 30, 2014, to identify RCTs comparing local infiltration analgesia or peripheral nerve block use in patients after THA. A total of 35 RCTs at low risk of bias based on the recommended Cochrane Collaboration risk assessment tool were included in the network meta-analysis (2296 patients). Primary outcomes for this review were patient pain scores at rest and cumulative opioid consumption, both assessed at 24 hours after THA. Because of substantial heterogeneity (variation of outcomes between studies) across included trials, a random effect model for meta-analysis was used to estimate the weighted mean difference (WMD) and 95% CI. The gray literature was searched with the same inclusion criteria as published trials. Only one unpublished trial (published abstract) fulfilled our criteria and was included in this review. All other studies included in this systematic review were full published articles. Bayesian network meta-analysis included all RCTs that compared local infiltration analgesia or peripheral nerve blocks with placebo (or no intervention), epidural analgesia, and intrathecal morphine.

RESULTS

Compared with placebo, local infiltration analgesia reduced patient pain scores (WMD, -0.61; 95% CI, -0.97 to -0.24; p = 0.001) and opioid consumption (WMD, -7.16 mg; 95% CI, -11.98 to -2.35; p = 0.004). Peripheral nerve blocks did not result in lower pain scores or reduced opioid consumption compared with placebo (WMD, -0.43; 95% CI, -0.99 to 0.12; p = 0.12 and WMD, -3.14 mg, 95% CI, -11.30 to 5.02; p = 0.45). However, network meta-analysis comparing local infiltration analgesia with peripheral nerve blocks through common comparators showed no differences between postoperative pain scores (WMD, -0.36; 95% CI, -1.06 to 0.31) and opioid consumption (WMD, -4.59 mg; 95% CI, -9.35 to 0.17), although rank-order analysis found local infiltration analgesia to be ranked first in more simulations than peripheral nerve blocks, suggesting that it may be more effective.

CONCLUSIONS

Using the novel statistical network meta-analysis approach, we found no differences between local infiltration analgesia and peripheral nerve blocks in terms of analgesia or opioid consumption 24 hours after THA; there was a suggestion of a slight advantage to peripheral nerve blocks based on rank-order analysis, but the effect size in question is likely not large. Given the slight difference between interventions, clinicians may choose to focus on other factors such as cost and intervention-related complications when debating which analgesic treatment to use after THA.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Calreticulin secures calcium-dependent nuclear pore competency required for cardiogenesis

Calreticulin deficiency causes myocardial developmental defects that culminate in an embryonic lethal phenotype. Recent studies have linked loss of this calcium binding chaperone to failure in myofibrillogenesis through an as yet undefined mechanism. The purpose of the present study was to identify cellular processes corrupted by calreticulin deficiency that precipitate dysregulation of cardiac myofibrillogenesis related to acquisition of cardiac phenotype. In an embryonic stem cell knockout model, calreticulin deficit (crt(-/-)) compromised nucleocytoplasmic transport of nuclear localization signal-dependent and independent pathways, disrupting nuclear import of the cardiac transcription factor MEF2C. The expression of nucleoporins and associated nuclear transport proteins in derived crt(-/-) cardiomyocytes revealed an abnormal nuclear pore complex (NPC) configuration. Altered protein content in crt(-/-) cells resulted in remodeled NPC architecture that caused decreased pore diameter and diminished probability of central channel occupancy versus wild type counterparts. Ionophore treatment of impaired calcium handling in crt(-/-) cells corrected nuclear pore microarchitecture and rescued nuclear import resulting in normalized myofibrillogenesis. Thus, calreticulin deficiency alters nuclear pore function and structure, impeding myofibrillogenesis in nascent cardiomyocytes through a calcium dependent mechanism. This essential role of calreticulin in nucleocytoplasmic communication competency ties its regulatory action with proficiency of cardiac myofibrillogenesis essential for proper cardiac development.

Modeling structural and functional deficiencies of RBM20 familial dilated cardiomyopathy using human induced pluripotent stem cells

Dilated cardiomyopathy (DCM) is a leading cause of heart failure. In families with autosomal-dominant DCM, heterozygous missense mutations were identified in RNA-binding motif protein 20 (RBM20), a spliceosome protein induced during early cardiogenesis. Dermal fibroblasts from two unrelated patients harboring an RBM20 R636S missense mutation were reprogrammed to human induced pluripotent stem cells (hiPSCs) and differentiated to beating cardiomyocytes (CMs). Stage-specific transcriptome profiling identified differentially expressed genes ranging from angiogenesis regulator to embryonic heart transcription factor as initial molecular aberrations. Furthermore, gene expression analysis for RBM20-dependent splice variants affected sarcomeric (TTN and LDB3) and calcium (Ca(2+)) handling (CAMK2D and CACNA1C) genes. Indeed, RBM20 hiPSC-CMs exhibited increased sarcomeric length (RBM20: 1.747 ± 0.238 µm versus control: 1.404 ± 0.194 µm; P < 0.0001) and decreased sarcomeric width (RBM20: 0.791 ± 0.609 µm versus control: 0.943 ± 0.166 µm; P < 0.0001). Additionally, CMs showed defective Ca(2+) handling machinery with prolonged Ca(2+) levels in the cytoplasm as measured by greater area under the curve (RBM20: 814.718 ± 94.343 AU versus control: 206.941 ± 22.417 AU; P < 0.05) and higher Ca(2+) spike amplitude (RBM20: 35.281 ± 4.060 AU versus control:18.484 ± 1.518 AU; P < 0.05). β-adrenergic stress induced with 10 µm norepinephrine demonstrated increased susceptibility to sarcomeric disorganization (RBM20: 86 ± 10.5% versus control: 40 ± 7%; P < 0.001). This study features the first hiPSC model of RBM20 familial DCM. By monitoring human cardiac disease according to stage-specific cardiogenesis, this study demonstrates RBM20 familial DCM is a developmental disorder initiated by molecular defects that pattern maladaptive cellular mechanisms of pathological cardiac remodeling. Indeed, hiPSC-CMs recapitulate RBM20 familial DCM phenotype in a dish and establish a tool to dissect disease-relevant defects in RBM20 splicing as a global regulator of heart function.

Systems biology surveillance decrypts pathological transcriptome remodeling

BACKGROUND

Pathological cardiac development is precipitated by dysregulation of calreticulin, an endoplasmic reticulum (ER)-resident calcium binding chaperone and critical contributor to cardiogenesis and embryonic viability. However, pleiotropic phenotype derangements induced by calreticulin deficiency challenge the identification of specific downstream transcriptome elements that direct proper cardiac formation. Here, differential transcriptome navigation was used to diagnose high priority calreticulin domain-specific gene expression changes and decrypt complex cardiac-specific molecular responses elicited by discrete functional regions of calreticulin.

METHODS

Wild type (WT), calreticulin-deficient (CALR(-/-)), and calreticulin truncation variant (CALR(-/-)-NP and CALR(-/-)-PC) pluripotent stem cells were used to investigate molecular remodeling underlying a model of cardiopathology. Bioinformatic deconvolution of isolated transcriptomes was performed to identify predominant expression trends, gene ontology prioritizations, and molecular network features characteristic of discrete cell types.

RESULTS

Stem cell lines with wild type (WT), calreticulin-deficient (CALR(-/-)) genomes, as well as calreticulin truncation variants exclusively expressing either the chaperoning (CALR(-/-)-NP) or the calcium binding (CALR(-/-)-PC) domain exhibited characteristic molecular signatures determined by unsupervised agglomerative clustering. Kohonen mapping of RNA expression changes identified transcriptome dynamics that segregated into 12 discrete gene expression meta-profiles which were enriched for regulation of Eukaryotic Initiation Factor 2 (EIF2) signaling. Focused examination of domain-specific gene ontology remodeling revealed a general enrichment of Cardiovascular Development in the truncation variants, with unique prioritization of "Cardiovascular Disease" exclusive to the cohort of down regulated genes of the PC truncation variant. Molecular cartography of genes that comprised this cardiopathological category revealed uncharacterized and novel gene relationships, with identification of Pitx2 as a critical hub within the topology of a CALR(-/-) compromised network.

CONCLUSIONS

Diagnostic surveillance, through an algorithm that integrates pluripotent stem cell transcriptomes with advanced high throughput assays and computational bioinformatics, revealed collective gene expression network changes that underlie differential phenotype development. Stem cell transcriptomes provide a deep collective molecular index that reflects ad hoc robustness of the pluripotent gene network. Remodeling events such as monogenic lesions provide a background by which high priority candidate disease effectors and regulators can be identified, demonstrated here by a molecular profiling algorithm that decrypts pluripotent wild type versus disrupted genomes.

Regenerative Therapy Prevents Heart Failure Progression in Dyssynchronous Nonischemic Narrow QRS Cardiomyopathy

Background

Cardiac resynchronization therapy using bi-ventricular pacing is proven effective in the management of heart failure (HF) with a wide QRS-complex. In the absence of QRS prolongation, however, device-based resynchronization is reported unsuitable. As an alternative, the present study tests a regenerative cell-based approach in the setting of narrow QRS-complex HF.

Methods and Results

Progressive cardiac dyssynchrony was provoked in a chronic transgenic model of stress-triggered dilated cardiomyopathy. In contrast to rampant end-stage disease afflicting untreated cohorts, stem cell intervention early in disease, characterized by mechanical dyssynchrony and a narrow QRS-complex, aborted progressive dyssynchronous HF and prevented QRS widening. Stem cell-treated hearts acquired coordinated ventricular contraction and relaxation supporting systolic and diastolic performance. Rescue of contractile dynamics was underpinned by a halted left ventricular dilatation, limited hypertrophy, and reduced fibrosis. Reverse remodeling reflected a restored cardiomyopathic proteome, enforced at systems level through correction of the pathological molecular landscape and nullified adverse cardiac outcomes. Cell therapy of a dyssynchrony-prone cardiomyopathic cohort translated prospectively into improved exercise capacity and prolonged survivorship.

Conclusions

In narrow QRS HF, a regenerative approach demonstrated functional and structural benefit, introducing the prospect of device-autonomous resynchronization therapy for refractory disease.

Inhibition of DNA topoisomerase II selectively reduces the threat of tumorigenicity following induced pluripotent stem cell-based myocardial therapy

The advent of induced pluripotent stem cell (iPSC) technology creates new opportunities for transplant-based therapeutic strategies. The potential for clinical translation is currently hindered by the risk of dysregulated cell growth. Pluripotent stem cells reprogrammed by three-factor (Sox2, Klf, and Oct4) and four-factor (Sox2, Klf, Oct4, and c-Myc) strategies result in the capacity for teratogenic growth from residual pluripotent progeny upon in vivo transplantation. However, these pluripotent stem cells also have a stage-specific hypersensitivity to DNA-damaging agents that may allow separation of lineage-specific therapeutic subpopulation of cells. We aimed to demonstrate the selective effect of DNA topoisomerase II inhibitor, etoposide, in eliminating pluripotent cells in the early cardiac progenitor population thus decreasing the effect of teratoma formation. Immunodeficient murine hearts were infarcted and received implantation of a therapeutic dose of cardiac progenitors derived from partially differentiated iPSCs. Etoposide-treated cell implantation reduced mass formation in the intracardiac and extracardiac chest cavity compared with the same dose of iPSC-derived cardiac progenitors in the control untreated group. In vivo bioluminescence imaging confirmed the localization and engraftment of transplanted cells in the myocardium postinjection in both groups. Comparatively, the equivalent cell population without etoposide treatment demonstrated a greater incidence and size of teratoma formation. Hence, pretreatment with genotoxic etoposide significantly lowered the threat of teratogenicity by purging the contaminating pluripotent cells, establishing an adjunctive therapy to further harness the clinical value of iPSC-derived cardiac regeneration.