Temporal Single-Cell Sequencing Analysis Reveals That GPNMB-Expressing Macrophages Potentiate Muscle Regeneration.

Macrophages play a crucial role in coordinating the skeletal muscle repair response, but their phenotypic diversity and the transition of specialized subsets to resolution-phase macrophages remain poorly understood. To address this issue, we induced injury and performed single-cell RNA sequencing on individual cells in skeletal muscle at different time points. Our analysis revealed a distinct macrophage subset that expressed high levels of Gpnmb and that coexpressed critical factors involved in macrophage-mediated muscle regeneration, including Igf1, Mertk, and Nr1h3. Gpnmb gene knockout inhibited macrophage-mediated efferocytosis and impaired skeletal muscle regeneration. Functional studies demonstrated that GPNMB acts directly on muscle cells in vitro and improves muscle regeneration in vivo. These findings provide a comprehensive transcriptomic atlas of macrophages during muscle injury, highlighting the key role of the GPNMB macrophage subset in regenerative processes. Targeting GPNMB signaling in macrophages could have therapeutic potential for restoring skeletal muscle integrity and homeostasis.

Endoscopic ultrasonography-related diagnostic accuracy and clinical significance on small rectal neuroendocrine neoplasms.

This research aimed to examine the diagnostic accuracy and clinical significance of endoscopic ultrasonography (EUS) in the context of small rectal neuroendocrine neoplasms (NENs). A total of 108 patients with rectal subepithelial lesions (SELs) with a diameter of < 20 mm were included in the analysis. The diagnosis and depth assessment of EUS was compared to the histology findings. The prevalence of NENs in rectal SELs was 78.7% (85/108). The sensitivity of EUS in detecting rectal NENs was 98.9% (84/85), while the specificity was 52.2% (12/23). Overall, the diagnostic accuracy of EUS in identifying rectal NENs was 88.9% (96/108). The overall accuracy rate for EUS in assessing the depth of invasion in rectal NENs was 92.9% (78/84). Therefore, EUS demonstrates reasonable diagnostic accuracy in detecting small rectal NENs, with good sensitivity but inferior specificity. EUS may also assist physicians in assessing the depth of invasion in small rectal NENs before endoscopic excision.

Modulation of experimental acute lung injury by exosomal miR-7704 from mesenchymal stromal cells acts through M2 macrophage polarization.

Acute lung injury (ALI) is a life-threatening condition with limited treatment options. The pathogenesis of ALI involves macrophage-mediated disruption and subsequent repair of the alveolar barriers, which ultimately results in lung damage and regeneration, highlighting the pivotal role of macrophage polarization in ALI. Although exosomes derived from mesenchymal stromal cells have been established as influential modulators of macrophage polarization, the specific role of exosomal microRNAs (miRNAs) remains underexplored. This study aimed to elucidate the role of specific exosomal miRNAs in driving macrophage polarization, thereby providing a reference for developing novel therapeutic interventions for ALI. We found that miR-7704 is the most abundant and efficacious miRNA for promoting the switch to the M2 phenotype in macrophages. Mechanistically, we determined that miR-7704 stimulates M2 polarization by inhibiting the MyD88/STAT1 signaling pathway. Notably, intra-tracheal delivery of miR-7704 alone in a lipopolysaccharide-induced murine ALI model significantly drove M2 polarization in lung macrophages and remarkably restored pulmonary function, thus increasing survival. Our findings highlight miR-7704 as a valuable tool for treating ALI by driving the beneficial M2 polarization of macrophages. Our findings pave the way for deeper exploration into the therapeutic potential of exosomal miRNAs in inflammatory lung diseases.

Immunotherapy-associated symptoms, distress, financial toxicity and unmet supportive care needs of patients with cancer.

PURPOSE: To examine the unmet care needs (i.e., overall needs and need subdomains [physical and daily living needs, psychological and emotional needs, care and support needs, and health-system and informational needs]) of patients with cancer undergoing immunotherapy alone or in combination with other anticancer therapies, as well as related influencing factors. METHODS: A cross-sectional design was adopted. Cancer patients who received immunotherapy completed consent and questionnaires. Unmet care needs were evaluated with the Chinese version of the Supportive Care Needs Survey Screening Tool, symptom severity with the Symptom Severity Scale, distress severity with the Distress Thermometer Scale, and financial toxicity using the Financial Toxicity - Functional Assessment of Chronic Illness Therapy Questionnaire. RESULTS: In total, 105 patients were surveyed. The most frequently reported unmet needs were psychological and emotional needs (56.2%) followed by health-system and informational needs (36.2%). The major factors associated with unmet care needs and their subdomains were years of education, symptoms, distress, and financial toxicity. Years of education predicted overall unmet care needs, psychological and emotional needs, and care and support needs; symptoms predicted overall unmet care needs and all four subdomains; distress predicted psychological and emotional needs and health-system and informational needs; and financial toxicity predicted overall needs and psychological and emotional needs. CONCLUSIONS: Patients with higher education, severe symptoms, distress, and financial toxicity reported more unmet care needs. The findings of this study could be incorporated into immunotherapy-related clinical practice guidelines and future interventions to improve the quality of cancer care.

Laser Speckle Contrast Imaging Guides Needling Treatment of Vascular Complications from Dermal Fillers.

BACKGROUND: Although laser Doppler imaging (LDI) accurately delineates a hypoperfused area to help target hyaluronidase treatment, laser speckle contrast imaging (LSCI) is more appropriate for assessing microvascular hemodynamics and has greater reproducibility than LDI. This study investigated the use of LSCI in the evaluation and treatment of six patients who developed vascular complications after facial dermal filler injections. METHODS: The areas of vascular occlusion were accurately defined in real time by LSCI and were more precise than visual inspections or photographic evidence for guiding needling and hyaluronidase treatment. RESULTS: All patients had achieved satisfactory outcomes as early as Day 2 of treatment and no procedure-related complications were reported after a median follow-up of 9.5 (7-37) days. CONCLUSION: LSCI accurately and noninvasively delineated vascular occlusions in real time among patients experiencing complications of facial dermal filler injections. Moreover, LSCI was more accurate than visual and photographic evaluations. Clinicians can use LSCI to reliably follow-up therapeutic outcomes after salvage interventions for vascular occlusions. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Enhanced axon outgrowth of spinal motor neurons in co-culturing with dorsal root ganglions antagonizes the growth inhibitory environment.

Introduction: Forming a bridge made of functional axons to span the lesion is essential to reconstruct the motor circuitry following spinal cord injury (SCI). Dorsal root ganglion (DRG) axons are robust in axon growth and have been proved to facilitate the growth of cortical neurons in a process of axon-facilitated axon regeneration. However, whether DRG transplantation affects the axon outgrowth of spinal motor neurons (SMNs) that play crucial roles in motor circuitry remains unclear. Methods: We investigated the axonal growth patterns of co-cultured DRGs and SMN aggregates (SMNAs) taking advantage of a well-designed 3D-printed in vitro system. Chondroitin sulphate proteoglycans (CSPG) induced inhibitory matrix was introduced to imitate the inhibitory environment following SCI. Axonal lengths of DRG, SMNA or DRG & SMNA cultured on the permissive or CSPG induced inhibitory matrix were measured and compared. Results: Our results indicated that under the guidance of full axonal connection generated from two opposing populations of DRGs, SMNA axons were growth-enhanced and elongated along the DRG axon bridge to distances that they could not otherwise reach. Quantitatively, the co-culture increased the SMNA axonal length by 32.1 %. Moreover, the CSPG matrix reduced the axonal length of DRGs and SMNAs by 46.2 % and 17.7 %, respectively. This inhibitory effect was antagonized by the co-culture of DRGs and SMNAs. Especially for SMNAs, they extended the axons across the CSPG-coating matrix, reached the lengths close to those of SMNAs cultured on the permissive matrix alone. Conclusions: This study deepens our understanding of axon-facilitated reconstruction of the motor circuitry. Moreover, the results support SCI treatment utilizing the enhanced outgrowth of axons to restore functional connectivity in SCI patients.

Single-cell transcriptome analysis reveals the effectiveness of cytokine priming irrespective of heterogeneity in mesenchymal stromal cells.

BACKGROUND AIMS: Mesenchymal stromal cells (MSCs) are recognized as a potential cell-based therapy for regenerative medicine. Short-term inflammatory cytokine pre-stimulation (cytokine priming) is a promising approach to enhance regenerative efficacy of MSCs. However, it is unclear whether their intrinsic heterogenic nature causes an unequal response to cytokine priming, which might blunt the accessibility of clinical applications. METHODS: In this study, by analyzing the single-cell transcriptomic landscape of human bone marrow MSCs from a naïve to cytokine-primed state, we elucidated the potential mechanism of superior therapeutic potential in cytokine-primed MSCs. RESULTS: We found that cytokine-primed MSCs had a distinct transcriptome landscape. Although substantial heterogeneity was identified within the population in both naïve and primed states, cytokine priming enhanced the several characteristics of MSCs associated with therapeutic efficacy irrespective of heterogeneity. After cytokine-priming, all sub-clusters of MSCs possessed high levels of immunoregulatory molecules, trophic factors, stemness-related genes, anti-apoptosis markers and low levels of multi-lineage and senescence signatures, which are critical for their therapeutic potency. CONCLUSIONS: In conclusion, our results provide new insights into MSC heterogeneity under cytokine stimulation and suggest that cytokine priming reprogrammed MSCs independent of heterogeneity.

Immunometabolism of macrophages regulates skeletal muscle regeneration.

Sarcopenia is an age-related progressive loss of skeletal muscle mass, quality, and strength disease. In addition, sarcopenia is tightly correlated with age-associated pathologies, such as sarcopenic obesity and osteoporosis. Further understanding of disease mechanisms and the therapeutic strategies in muscle regeneration requires a deeper knowledge of the interaction of skeletal muscle and other cells in the muscle tissue. Skeletal muscle regeneration is a complex process that requires a series of highly coordinated events involving communication between muscle stem cells and niche cells, such as muscle fibro/adipogenic progenitors and macrophages. Macrophages play a critical role in tissue regeneration and the maintenance of muscle homeostasis by producing growth factors and cytokines that regulate muscle stem cells and myofibroblast activation. Furthermore, the aging-related immune dysregulation associated with the release of trophic factors and the polarization in macrophages transiently affect the inflammatory phase and impair muscle regeneration. In this review, we focus on the role and regulation of macrophages in skeletal muscle regeneration and homeostasis. The aim of this review is to highlight the important roles of macrophages as a therapeutic target in age-related sarcopenia and the increasing understanding of how macrophages are regulated will help to advance skeletal muscle regeneration.

Safety and Efficacy of Submuscular Implantation With Resterilized Cardiac Implantable Electronic Device in Patients With Device Infection: A Retrospective Observational Study in Taiwan.

Background: Reuse of cardiac implantable electronic devices (CIEDs) can reduce the cost of using these expensive devices. However, whether resterilized CIEDs will increase the risk of reinfection in patients with previous device infection remains unknown. The aim of the present study is to compare the reinfection rates in patients who had initial CIED infection and underwent reimplantation of resterilized CIEDs or new devices. Methods: Data from patients with initial CIED infection who received debridement of the infected pocket and underwent reimplantation of new or resterilized CIEDs at MacKay Memorial Hospital, Taipei, Taiwan, between January 2014 and June 2019 were retrospectively analyzed. Patient characteristics, relapse rates of infection, and potential contributing factors to the infection risk were examined. Results: Twenty-seven patients with initial CIED infection and reimplanted new CIEDs (n = 11) or resterilized CIEDs (n = 16) were included. During the 2-year follow-up, there were 1 (9.1%) and 2 (12.5%) infection relapses in the new and resterilized CIED groups, respectively. No relapse occurred for either group if the lead was completely removed or cut short. The median duration between debridement and device reimplantation in patients with infection relapse vs patients without relapse was 97 vs 4.5 days for all included patients, and 97 vs 2 days and 50.5 vs 5.5 days for the new and resterilized CIED groups, respectively. Conclusions: Subpectoral reimplanting of resterilized CIEDs in patients with previous device infection is safe and efficacious. With delicate debridement and complete extraction of the leads, the CIED pocket infection relapse risk can be greatly decreased.

Efficacy and safety of pectoralis muscle flap combined rectus abdominis muscle sheath fasciocutaneous flap for reconstruction of sternal infection.

Few studies have assessed the efficacy and safety of reconstruction of sternal infection using a pectoralis muscle flap combined with a rectus abdominis muscle (RAM) sheath fasciocutaneous flap. We report here our experience with this procedure to reconstruct the sternal defect in patients (n = 46) with a deep sternal wound infection (DSWI) after cardiac surgery. After wound reconstruction, the proportion of prolonged mechanical ventilation use and intensive care unit (ICU) stay were 17.4% (n = 8) and 21.7% (n = 10), respectively. The 30-day all-cause mortality was 15.2%; recurrence rate was 17.4%; postoperative complications were 15.2%; and median hospital stay was 31 (0-157) days. Multivariate logistic regression analysis revealed that hypertension (ß = 21.32, 95%CI 4.955-37.68, P = .014), drainage-tube use (ß = 0.944, 95%CI 0.273-1.614, P = .008), and prolonged intensive care unit stay (ß = 53.65, 95%CI 31.353-75.938, P < .001) were significantly correlated with hospital stay. In conclusion, a procedure including surgical debridement, sternal reconstruction with bilateral PM and RAM sheath flap, long-term antibiotics, and adequate drainage is a beneficial technique in the reconstruction of deep sternal wound infection after cardiac surgery. Duration of drainage tube use may be as an index for a hospital stay or wound healing.

Cadmium induces the expression of Interleukin-6 through Heme Oxygenase-1 in HK-2 cells and Sprague-Dawley rats.

Cadmium is toxic to the kidney through mechanisms involving oxidative stress and inflammation. We studied reciprocal crosstalk among the oxidative stress, inflammation, and the nuclear Nrf2 pathway in cadmium-induced nephrotoxicity on HK-2 human renal proximal tubular epithelial cells. Cadmium chloride (CdCl2) caused cell viability loss, Reactive Oxygen Species (ROS) generation, glutathione reduction, and Interleukin-6 (IL-6) expression, accompanied by Nrf2 activation and Heme Oxygenase-1 (HO-1) expression. Pharmacological treatments demonstrated cytotprotective and anti-inflammatory effects of Nrf2 activation. Intriguingly, inhibition of HO-1 activity mitigated cell viability loss and IL-6 expression in CdCl2-treated cells. Parallel attenuation by HO-1 inhibitor was demonstrated in cadmium-induced ROS generation and glutathione reduction. CdCl2-treated cells also increased levels of ferrous iron, cGMP, Mitogen-Activated Protein Kinases phosphorylation, as well as NF-κB DNA-binding activity. These increments were mitigated by antioxidant N-Acetyl Cysteine, HO-1 inhibitor SnPP, and PKG inhibitor KT5823, and were mimicked by the Carbon Monoxide-releasing compound. In the kidney cortex of CdCl2-exposed Sprague-Dawley rats, we found similar renal injury, histological changes, ROS generation, IL-6 expression, and accompanied pro-oxidant and pro-inflammatory changes. These observations indicated that cadmium-induced nephrotoxicity was associated with oxidative stress and inflammation, and HO-1 likely acts as a linking molecule to induce nephrotoxicity-associated IL-6 expression upon cadmium exposure.

Kimura Disease of the Thigh Treated With Surgical Excision and Dupilumab.

ABSTRACT: Kimura disease (KD) is a rare, chronic inflammatory disorder presenting with solitary or multiple masses. Treatment options include surgical excision, corticosteroids, and radiotherapy; however, optimal therapy remains to be established. Moreover, efficacy of a humanized monoclonal antibody, dupilumab (Dupixent), requires to be demonstrated. Here, we present a 36-year-old male patient with an enlarging mass in the left medial thigh and chronic eczema over the abdomen and lower legs. Kimura disease was diagnosed after surgical excision. Postoperative treatment with dupilumab was applied with an initial dose of 600 mg followed by 300 mg every 2 weeks for 8 months. No recurrence of KD was observed in the 1-year follow-up. The eczematous lesions improved greatly. To our knowledge, this is the first report of using dupilumab for treating KD.

Jak2 Inhibitor AG490 Improved Poststroke Central and Peripheral Inflammation and Metabolic Abnormalities in a Rat Model of Ischemic Stroke.

Poststroke hyperglycemia and inflammation have been implicated in the pathogenesis of stroke. Janus Kinase 2 (Jak2), a catalytic signaling component for cytokine receptors such as Interleukin-6 (IL-6), has inflammatory and metabolic properties. This study aimed to investigate the roles of Jak2 in poststroke inflammation and metabolic abnormality in a rat model of permanent cerebral ischemia. Pretreatment with Jak2 inhibitor AG490 ameliorated neurological deficit, brain infarction, edema, oxidative stress, inflammation, caspase-3 activation, and Zonula Occludens-1 (ZO-1) reduction. Moreover, in injured cortical tissues, Tumor Necrosis Factor-α, IL-1ß, and IL-6 levels were reduced with concurrent decreased NF-κB p65 phosphorylation, Signal Transducers and Activators of Transcription 3 phosphorylation, Ubiquitin Protein Ligase E3 Component N-Recognin 1 expression, and Matrix Metalloproteinase activity. In the in vitro study on bEnd.3 endothelial cells, AG490 diminished IL-6-induced endothelial barrier disruption by decreasing ZO-1 decline. Metabolically, administration of AG490 lowered fasting glucose, with improvements in glucose intolerance, plasma-free fatty acids, and plasma C Reactive Proteins. In conclusion, AG490 improved the inflammation and oxidative stress of neuronal, hepatic, and muscle tissues of stroke rats as well as impairing insulin signaling in the liver and skeletal muscles. Therefore, Jak2 blockades may have benefits for combating poststroke central and peripheral inflammation, and metabolic abnormalities.

Laser Doppler Imaging for Treating Vascular Complications from Procedures Involving Dermal Fillers: Case Series and Literature Review.

Vascular occlusion is a rare but severe complication of dermal filler injections. Early treatment of this complication produces better outcomes. Current diagnostic methods for vascular occlusion in the skin are subjective and imprecise; these include capillary refill time, skin color, and reports of pain. This study aimed to assess the use of laser Doppler imaging (LDI) in the evaluation and treatment of vascular complications caused by dermal filler injections. This retrospective study used laser Doppler imaging (LDI) in 13 patients who developed vascular occlusion after facial dermal filler injections, with subsequent follow-up. The precise areas of perfusion observed on LDI were compared with the findings of clinical and photographic evaluation. The results showed that LDI accurately identified areas of vascular occlusion and improved treatment precision among these thirteen patients. The procedure was more precise than visual inspection or photographic evidence. Satisfactory outcomes were achieved for all patients, and no procedure-related complications were reported. Collectively, LDI provides fast, noninvasive, and accurate delineation of areas of vascular occlusion caused by complications of dermal filler injections and avoids several subjective shortcomings of visual and photographic evaluations. Thus, LDI effectively tracks treatment outcomes. However, large-scale studies are required to confirm the present findings.

Percutaneous Debridement of and Fibrin Glue Injection Into a Pretibial Morel-Lavallée Lesion: A Case Report and Literature Review.

ABSTRACT: The Morel-Lavallée lesion (MLL) is a posttraumatic close degloving injury, which is often underdiagnosed at first. Patients with MLLs usually present with tender and enlarging soft tissue swelling with fluctuation, decreased skin sensation, ecchymosis, or even skin necrosis hours to days after the inciting injury. The lesion can lead to intractable morbidity if it remains untreated. There is no consensus regarding the treatment for MLL at present. Here, we report an MLL in the pretibial region of a 43-year-old woman who experienced a low-energy contusion in a motorbike accident. The pretibial lesion was diagnosed using sonography and fine-needle aspiration. We successfully treated the patient by performing percutaneous debridement via a small incision and injections of fibrin after conservative treatment failed. The method we herein propose achieved the goal of open surgical debridement, providing faster recovery and a high degree of patient comfort. We reviewed the available pertinent literature and propose our own treatment protocol with the aim to establish common therapies ofMLL.

Control of matrix stiffness promotes endodermal lineage specification by regulating SMAD2/3 via lncRNA LINC00458.

During endoderm formation, cell identity and tissue morphogenesis are tightly controlled by cell-intrinsic and cell-extrinsic factors such as biochemical and physical inputs. While the effects of biochemical factors are well studied, the physical cues that regulate cell division and differentiation are poorly understood. RNA sequencing analysis demonstrated increases of endoderm-specific gene expression in hPSCs cultured on soft substrate (Young's modulus, 3 ± 0.45 kPa) in comparison with hard substrate (Young's modulus, 165 ± 6.39 kPa). Further analyses revealed that multiple long noncoding RNAs (lncRNAs) were up-regulated on soft substrate; among them, LINC00458 was identified as a stiffness-dependent lncRNA specifically required for hPSC differentiation toward an early endodermal lineage. Gain- and loss-of-function experiments confirmed that LINC00458 is functionally required for hPSC endodermal lineage specification induced by soft substrates. Our study provides evidence that mechanical cues regulate the expression of LINC00458 and induce differentiation of hPSC into hepatic lineage progenitors.

Near Complete Recovery of Visual Acuity After Calcium Hydroxylapatite Injection-Related Vision Loss: A Case Report and Literature Review.

Injection of fillers has gained popularity over the past decades in aesthetic treatments. Calcium hydroxylapatite (CaHA; Radiesse) was introduced in the year 2003 and received approval from the Food and Drug Administration in 2006 for the treatment of moderate-to-severe wrinkles. The properties of CaHA include biostimulation, neocollagenesis, and stability over a long period. However, similar to other fillers, CaHA is associated with the risk of complications such as ecchymosis, inflammation, local infection, skin necrosis, and vascular occlusion. Iatrogenic vision loss remains the most devastating complication related to vascular occlusion. Development of vision impairment is associated with a relatively high risk of permanent damage to vision acuity and poor prognosis. The current report presents a case of a patient who suffered from skin necrosis, vision impairment, and ophthalmoplegia after the injection of CaHA into the nasal dorsum. Significant improvement in visual acuity was observed during hospitalization after the treatment. The patient recovered to near-normal visual acuity and completely recovered from ophthalmoplegia. We aimed to discuss the current treatment employed and review the literature on CaHA-related vision loss.

An early complication in the donor site of the medial sural artery perforator flap: necrosis of the medial head of gastrocnemius.

The relatively new medial sural artery perforator flap is increasingly being used for reconstruction. However, muscle necrosis of the medial head of gastrocnemius after MSAP flap harvest is a previously unnoticed early complication of the donor site. We present two cases of MSAP flap reconstruction that developed this early complication.

[A novel calcium phosphate cement pre-loaded with chitosan and small molecule adenosine for repairing large cranial defects in rats].

OBJECTIVE: To evaluate the effect of a novel biomaterial in repairing large cranial defects in rats. METHODS: Eighteen SD rats were used to establish rat modes of large cranial defect (8 mm in diameter). The rat models were randomized into 3 groups and the cranial defects were repaired using different scaffold materials, namely CPC paste prepared with distilled water (CPC control group), CPC paste mixed with 10% chitosan (CPC/CN group), or CPC paste with 10% chitosan and 300 mg adenosine (CPC/CN/AD group). The defects were examined 12 weeks after the surgery with X-ray, CT, HE staining and quantitative assessments. RESULTS: X-ray showed that the defect was repaired in all the groups. The fracture line became obscure and the defects were almost fully repaired by regenerated bone tissues in CPC/CN/AD group, which was consistent with CT findings. In all the 3 groups, HE staining revealed the presence of new bones in the defects and new vessels in and around the new bones without inflammatory cells. The new bone area was significantly greater in CPC/CN/AD group than in CPC/CN group and CPC control group (P<0.05). The new vessel density was the highest in CPC/CN/AD group (P>0.05) but similar between CPC/CN group and CPC control group (P>0.05). CONCLUSION: This novel calcium phosphate cement pre-loaded with chitosan and small molecule adenosine can better promote bone regeneration than calcium phosphate cement for repairing large bone defects to serve as a good replacement material for bone regeneration.

Historical Perspectives and Advances in Mesenchymal Stem Cell Research for the Treatment of Liver Diseases.

Liver transplantation is the only effective therapy for patients with decompensated cirrhosis and fulminant liver failure. However, due to a shortage of donor livers and complications associated with immune suppression, there is an urgent need for new therapeutic strategies for patients with end-stage liver diseases. Given their unique function in self-renewal and differentiation potential, stem cells might be used to regenerate damaged liver tissue. Recent studies have shown that stem cell-based therapies can improve liver function in a mouse model of hepatic failure. Moreover, acellular liver scaffolds seeded with hepatocytes produced functional bioengineered livers for organ transplantation in preclinical studies. The therapeutic potential of stem cells or their differentiated progenies will depend on their capacity to differentiate into mature and functional cell types after transplantation. It will also be important to devise methods to overcome their genomic instability, immune reactivity, and tumorigenic potential. We review directions and advances in the use of mesenchymal stem cells and their derived hepatocytes for liver regeneration. We also discuss the potential applications of hepatocytes derived from human pluripotent stem cells and challenges to using these cells in treating end-stage liver disease.