Comparative evaluation of quality of life in oral cancer patients undergoing 3-dimensional conformal radiation therapy with or without concomitant chemotherapy - A longitudinal study.

OBJECTIVES: To assess and compare the quality of life (QOL) in Oral Cancer patients undergoing 3-DCRT with or without concomitant Chemotherapy at three different time intervals. MATERIALS AND METHODS: This unicentric longitudinal study included 50 patients of oral cancer undergoing 3-DCRT with or without concomitant chemotherapy. QOL was recorded using the EORTC H and N 35 Questionnaire at baseline, end of treatment (EOT), and 3 months after treatment. RESULTS: Maximum deterioration of most QOL domains were noted at End of treatment (EOT) in all the patients. A highly statistically significant difference was noted between different time intervals with the highest scores noted at the EOT (P < 0.01). There was a statistically significant difference in patients undergoing 3DCRT with chemotherapy when compared to those with 3DCRT without chemotherapy (P < 0.05). CONCLUSION: There is substantial deterioration in QOL at the EOT after head-neck irradiation by 3-DCRT with or without concomitant Chemotherapy although it gradually improves over time. However, 3DCRT results in clinically meaningful and statistically better QOL scores at 3 months after treatment compared to baseline and EOT.

Assessment of Ploidy Status in Oral Potentially Malignant Disorders - A Systematic Review.

Malignant and potentially malignant epithelial lesions are often associated with various abnormalities such as epithelial dysplasia, abnormal DNA content, loss of heterozygosity, and chromosomal number aberrations. Screening and early detection of such abnormalities facilitates proper care and also helps to prevent further progression of potentially malignant lesions to malignancy. In such way, the presence of DNA aneuploidy in oral potentially malignant disorders (OPMDs) may serve as an indicator for the malignant transforming potential. Various assessment methods have been proposed to find the DNA ploidy status of cells. This current systematic review is mainly designed to assess the importance of ploidy status in OPMD while measuring the feasibility of using this biomarker for evaluating the hazard of malignant transformation. As an upshot of this systematic review, we can conclude that use of DNA ploidy status can serve as an independent bio-marker for predicting the malignant transformation of lesions. Furthermore, as a future scope the use of DNA ploidy analysis in normal mucosa of smokers will help to assess the malignancy risk and this technique might also help to predict the genetic predisposition of patients with malignancy.

Basal cell adenoma of the floor of the mouth masquerading as ranula- A rare case in an unusual location.

A 65-year-old female patient with a history of wearing a denture for 15 years reported with a complaint of pain in the floor of the mouth. On examination, a swelling measuring about 2.2 X1.2 cms was noted in the floor of the mouth on the left side. The lesion was excised under local anesthesia. Histopathology revealed a cystic lesion with basaloid cells arranged in tubules, nests and cribriform pattern. A diagnosis of basal cell adenoma was made and confirmed by immunohistochemistry. We report a rare case of Basal Cell Adenoma of the floor of the mouth which mimicked a ranula. The predominantly cystic nature of this basaloid tumor posed a diagnostic challenge. Histopathological and immunohistochemical analysis to arrive at a definitive diagnosis aid in treatment planning and prognostication.

Synoptic review on existing and potential sources for bias in dental research methodology with methods on their prevention and remedies.

The results of years of dental study serve as the foundation for the practise of medicine and, for that matter, dentistry. Doctors may have their own preferences for techniques and materials, but whether directly or indirectly, their decisions are influenced by systematic reviews and meta-analyses. However, due to poorly conducted or presented research, this very basic foundation may not be reliable. Bias in research is one of several factors that might make study results or research itself unreliable. Bias can be introduced into research at many stages, deliberately or unknowingly. Bias can appear at any point during the research process, even before the study itself begins. There are many biases in research, but some of them are more relevant to dentistry research than others. Because it is said that "eyes see what the mind knows", it is essential to have a complete understanding of the different types of bias, how and when they get entrenched, and what steps may be taken to prevent or lessen them if they do occur. This comprehensive summary of bias in dentistry research is provided by this synoptic review. The goal is to identify gaps and measures that have been taken-or that should have been taken-by providing both descriptive and evaluative summaries, as well as examples from the literature, when needed.

Comparative evaluation of oral mucositis in oral cancer patients undergoing 3-dimensional conformal radiation therapy and intensity modulated radiation therapy with or without chemotherapy.

Context: Oral cancer is a significant cause of death across the world. A combined multimodal approach integrating surgery and radiation therapy (RT) with or without chemotherapy (CT) is commonly employed in advanced oral cancer to prevent recurrences and locoregional spread. Oral mucositis is a common acute toxicity reported in patients undergoing RT and CT. The delivery of optimal cancer therapy protocols is compromised due to morbidity caused by oral mucositis. Aims: To compare the severity of oral mucositis in oral cancer patients undergoing 3-Dimensional Conformal Radiation Therapy (3DCRT) and Intensity Modulated Radiation Therapy (IMRT) with or without concomitant CT. Settings and Design: This was a prospective, unicentric and longitudinal study conducted in a cancer centre. Methods and Material: One hundred four patients with locally advanced oral cancer were enrolled in this study. Fifty-two patients were treated with IMRT and 52 patients with 3DCRT to a dose of >60 Gy, along with concurrent cisplatin weekly CT. Mucositis was recorded before the start, in the end, 1 month, and 3 months post-chemoradiotherapy treatment. Statistical Analysis Used: Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) software (v. 21.0, Chicago. 2012). Descriptive and frequency statistics were performed for different parameters assessed in 3DCRT and IMRT group. Results: Grade 3 mucositis was the most predominant grade observed in both groups at the end of treatment. Thirty-six patients (69.3%) versus 24 patients (46.1%) developed grade 3 mucositis in 3DCRT and IMRT group, respectively (P = 0.013). Healing was better with IMRT group when compared to 3DCRT group 1 month and 3 months post-RT. Mucositis was severe in patients undergoing concomitant CT. Conclusions: IMRT reduced the incidence of severe mucositis and also improved the treatment-compliance compared to 3DCRT in locally advanced head neck cancer patients treated by chemoradiotherapy.

Parkinson's disease motor symptoms rescue by CRISPRa-reprogramming astrocytes into GABAergic neurons.

Direct reprogramming based on genetic factors resembles a promising strategy to replace lost cells in degenerative diseases such as Parkinson's disease. For this, we developed a knock-in mouse line carrying a dual dCas9 transactivator system (dCAM) allowing the conditional in vivo activation of endogenous genes. To enable a translational application, we additionally established an AAV-based strategy carrying intein-split-dCas9 in combination with activators (AAV-dCAS). Both approaches were successful in reprogramming striatal astrocytes into induced GABAergic neurons confirmed by single-cell transcriptome analysis of reprogrammed neurons in vivo. These GABAergic neurons functionally integrate into striatal circuits, alleviating voluntary motor behavior aspects in a 6-OHDA Parkinson's disease model. Our results suggest a novel intervention strategy beyond the restoration of dopamine levels. Thus, the AAV-dCAS approach might enable an alternative route for clinical therapies of Parkinson's disease.

Generation of a NES-mScarlet Red Fluorescent Reporter Human iPSC Line for Live Cell Imaging and Flow Cytometric Analysis and Sorting Using CRISPR-Cas9-Mediated Gene Editing.

Advances in the regenerative stem cell field have propelled the generation of tissue-specific cells in the culture dish for subsequent transplantation, drug screening purposes, or the elucidation of disease mechanisms. One major obstacle is the heterogeneity of these cultures, in which the tissue-specific cells of interest usually represent only a fraction of all generated cells. Direct identification of the cells of interest and the ability to specifically isolate these cells in vitro is, thus, highly desirable for these applications. The type VI intermediate filament protein NESTIN is widely used as a marker for neural stem/progenitor cells (NSCs/NPCs) in the developing and adult central and peripheral nervous systems. Applying CRISPR-Cas9 technology, we have introduced a red fluorescent reporter (mScarlet) into the NESTIN (NES) locus of a human induced pluripotent stem cell (hiPSC) line. We describe the generation and characterization of NES-mScarlet reporter hiPSCs and demonstrate that this line is an accurate reporter of NSCs/NPCs during their directed differentiation into human midbrain dopaminergic (mDA) neurons. Furthermore, NES-mScarlet hiPSCs can be used for direct identification during live cell imaging and for flow cytometric analysis and sorting of red fluorescent NSCs/NPCs in this paradigm.

Circulating biomarkers in oral cancer: Unravelling the mystery.

Oral squamous cell carcinoma (OSCC) is among the most common malignancies and a leading cause of death in developing countries. Late diagnosis and regional and/or distant metastasis worsen the prognosis of this condition. Despite the advances in diagnostic modalities and management strategies, there is little improvement in the 5-year survival rate. A deeper insight into the molecular events of various tumours has enabled the use of minimally invasive methods for monitoring disease progression, prognostication and treatment monitoring. Although studies in OSCC are preliminary, the use of liquid biopsies has opened new frontiers for the development of biomarkers that can serve as alternatives to conventional biopsies and imaging methods. Circulating biomarkers in blood allow for the real-time monitoring of tumour and therapeutic responses. This review aims to outline the promises and challenges of circulating biomarkers in OSCC with special emphasis on circulating tumour cells, circulating tumor DNA, and exosomes.

Developmental pathways linked to the vulnerability of adult midbrain dopaminergic neurons to neurodegeneration.

The degeneration of dopaminergic and other neurons in the aging brain is considered a process starting well beyond the infantile and juvenile period. In contrast to other dopamine-associated neuropsychiatric disorders, such as schizophrenia and drug addiction, typically diagnosed during adolescence or young adulthood and, thus, thought to be rooted in the developing brain, Parkinson's Disease (PD) is rarely viewed as such. However, evidences have accumulated suggesting that several factors might contribute to an increased vulnerability to death of the dopaminergic neurons at an already very early (developmental) phase in life. Despite the remarkable ability of the brain to compensate such dopamine deficits, the early loss or dysfunction of these neurons might predispose an individual to suffer from PD because the critical threshold of dopamine function will be reached much earlier in life, even if the time-course and strength of naturally occurring and age-dependent dopaminergic cell death is not markedly altered in this individual. Several signaling and transcriptional pathways required for the proper embryonic development of the midbrain dopaminergic neurons, which are the most affected in PD, either continue to be active in the adult mammalian midbrain or are reactivated at the transition to adulthood and under neurotoxic conditions. The persistent activity of these pathways often has neuroprotective functions in adult midbrain dopaminergic neurons, whereas the reactivation of silenced pathways under pathological conditions can promote the survival and even regeneration of these neurons in the lesioned or aging brain. This article summarizes our current knowledge about signaling and transcription factors involved in midbrain dopaminergic neuron development, whose reduced gene dosage or signaling activity are implicated in a lower survival rate of these neurons in the postnatal or aging brain. It also discusses the evidences supporting the neuroprotection of the midbrain dopaminergic system after the external supply or ectopic expression of some of these secreted and nuclear factors in the adult and aging brain. Altogether, the timely monitoring and/or correction of these signaling and transcriptional pathways might be a promising approach to a much earlier diagnosis and/or prevention of PD.

Exploring a safer alternative to eosin in soft tissue staining.

Context: Hematoxylin-eosin (H&E) stain has stood the test of time as the standard stain for histologic examination of human tissues. Haematoxylin is a natural dye, on the contrary, its counterstain eosin is a synthetic dye which belongs to the xanthene group. Synthetic dyes are hazardous to human and animal health. With the increasing awareness of a green earth, it is advisable to use environment-friendly and biodegradable materials. Therefore, an attempt was made to develop as biofriendly substitute in the form of food colour as a counterstain for haematoxylin. Aim: To assess the staining ability of food colouring agents in routine staining and to compare its staining efficacy with Eosin. Settings and Design: Two food colours were obtained and stain was prepared by using 70% ethyl alcohol as counterstain for haematoxylin. Different tissue structures such as epithelium, keratin, collagen fibers, muscles, salivary glands, adipocytes, blood vessels, RBCs were observed and evaluated. Methods and Material: Group A -10 slides stained with green food colour, Group B - 10 slides stained with tomato red food colour and Group C - 10 slides stained with conventional H and E. The stained sections were assessed and graded for nuclear staining, cytoplasmic staining, clarity, uniformity and crispness of staining. Statistical Analysis Used: The non-parametric Kruskal-Wallis and Mann-Whitney U tests were performed for statistical analysis. Results: There was no statistically significant difference between the three study groups with respect to all the parameters except crispness of staining. The crispness of Tomato Red and H and E was better compared to green food colour. Conclusions: Food colouring agents can be used as a safe, biofriendly and inexpensive substitute to eosin in conventional soft tissue staining.

Expression of matrix metalloproteinase-9 in histological grades of oral squamous cell carcinoma: An immunohistochemical study.

CONTEXT: Oral squamous cell carcinoma (OSCC) is characterized by a high degree of local invasiveness and metastasis to cervical lymph nodes and distant sites. Degradation of extracellular matrix (ECM) requires the concerted action of several extracellular enzymes, the most prominent of which are matrix metalloproteinases (MMPs). Proteolytic degradation of ECM components by (MMP-9) facilitates carcinoma cell invasion, enhances angiogenesis and tumor progression. OBJECTIVE: To assess and correlate the immunohistochemical expression of MMP-9 with clinicopathological parameters and histological grades of OSCC. SETTINGS AND DESIGN: Thirty histopathologically diagnosed cases of OSCC including 12 cases of well-differentiated squamous cell carcinoma, 12 cases of moderately differentiated squamous cell carcinoma and 6 cases of poorly differentiated squamous cell carcinoma were included in the study group. MATERIALS AND METHODS: The samples were subjected to staining using monoclonal antibodies against MMP-9 and visualized using the polymer-HRP detection system. Expression of MMP-9 was assessed in tumor epithelium/parenchyma and connective tissue stroma separately, and the mean of both was considered as average MMP-9 expression. STATISTICAL ANALYSIS: The parametric independent samples "t" test, one-way ANOVA test and Pearson's correlation test were used for the statistical analysis. RESULTS: Immunoexpression of MMP-9 increased with advancing stage and histological grade of OSCC with statistically significant results. CONCLUSION: MMP-9 plays an important role in invasion and metastasis and can serve as an independent prognostic marker.

Assessment of podoplanin lymphatic vessel density in oral epithelial dysplasia.

Background: Oral squamous cell carcinoma (OSCC) can be preceded by the appearance of lesions which have the potential to develop into cancer. Recently, it was suggested that the tumor-associated lymphatic vessels formation plays an active role in tumor progression and metastasis of several human malignancies including OSCC. There is the view that, in an individual lesion, the more severe the dysplasia, the greater the likelihood is of progression to malignancy. Aim: This study is aimed to investigate podoplanin (PDPN) immunoexpression in lymphatic vessels of oral epithelial dysplasia (OED) and to assess the lymphatic vessel density (LVD) in histologic grades of OED. Materials and Methods: The study group comprised thirty histopathologically diagnosed cases of OED with various grades of differentiation and thirty cases of clinically normal oral mucosa. After immunohistochemical staining, cases of OED were immunohistochemically analyzed quantitatively for PDPN (D2-40) LVD. Statistical Analysis: The statistical analysis was done using Kruskal Wallis analysis of variance; pair-wise Tukey's post hoc test was applied to evaluate the significant differences among the mean values in different groups. Results with "P < 0.05" were considered to be statistically significant at 95% of confidence level. Results: PDPN LVD scores increased with increasing grades of dysplasia. Pair-wise comparisons of the PDPN LVD scores and the histopathologic grades of OED were found to be statistically significant (P < 0.05). Conclusions: Increase in PDPN LVD in OED represents a promising tool for more wide spread studies of tumor lymphangiogenesis and its role in progression of dysplastic lesion to human cancer.

Dose-Dependent and Subset-Specific Regulation of Midbrain Dopaminergic Neuron Differentiation by LEF1-Mediated WNT1/b-Catenin Signaling.

The mesodiencephalic dopaminergic (mdDA) neurons, including the nigrostriatal subset that preferentially degenerates in Parkinson's Disease (PD), strongly depend on an accurately balanced Wingless-type MMTV integration site family member 1 (WNT1)/beta-catenin signaling pathway during their development. Loss of this pathway abolishes the generation of these neurons, whereas excessive WNT1/b-catenin signaling prevents their correct differentiation. The identity of the cells responding to this pathway in the developing mammalian ventral midbrain (VM) as well as the precise progression of WNT/b-catenin action in these cells are still unknown. We show that strong WNT/b-catenin signaling inhibits the differentiation of WNT/b-catenin-responding mdDA progenitors into PITX3+ and TH+ mdDA neurons by repressing the Pitx3 gene in mice. This effect is mediated by RSPO2, a WNT/b-catenin agonist, and lymphoid enhancer binding factor 1 (LEF1), an essential nuclear effector of the WNT/b-catenin pathway, via conserved LEF1/T-cell factor binding sites in the Pitx3 promoter. LEF1 expression is restricted to a caudolateral mdDA progenitor subset that preferentially responds to WNT/b-catenin signaling and gives rise to a fraction of all mdDA neurons. Our data indicate that an attenuation of WNT/b-catenin signaling in mdDA progenitors is essential for their correct differentiation into specific mdDA neuron subsets. This is an important consideration for stem cell-based regenerative therapies and in vitro models of neuropsychiatric diseases.

ß-catenin signaling modulates the tempo of dendritic growth of adult-born hippocampal neurons.

In adult hippocampal neurogenesis, stem/progenitor cells generate dentate granule neurons that contribute to hippocampal plasticity. The establishment of a morphologically defined dendritic arbor is central to the functional integration of adult-born neurons. We investigated the role of canonical Wnt/ß-catenin signaling in dendritogenesis of adult-born neurons. We show that canonical Wnt signaling follows a biphasic pattern, with high activity in stem/progenitor cells, attenuation in immature neurons, and reactivation during maturation, and demonstrate that this activity pattern is required for proper dendrite development. Increasing ß-catenin signaling in maturing neurons of young adult mice transiently accelerated dendritic growth, but eventually produced dendritic defects and excessive spine numbers. In middle-aged mice, in which protracted dendrite and spine development were paralleled by lower canonical Wnt signaling activity, enhancement of ß-catenin signaling restored dendritic growth and spine formation to levels observed in young adult animals. Our data indicate that precise timing and strength of ß-catenin signaling are essential for the correct functional integration of adult-born neurons and suggest Wnt/ß-catenin signaling as a pathway to ameliorate deficits in adult neurogenesis during aging.

Galectin-1 expression in oral squamous cell carcinoma: An immunohistochemical study.

CONTEXT: Oral squamous cell carcinoma (OSCC) of the head and neck are a heterogeneous group of neoplasms with an increasing rate of mortality and morbidity. OSCCs are characterized by a high degree of local invasiveness and metastasis to cervical lymph nodes but show a lower rate of distant metastasis. Galectin-1 (Gal-1), a ß-galactoside-binding lectin, is known to regulate tumor cell growth, angiogenesis, mediate cell-cell or cell-extracellular matrix adhesion and promote cancer cell migration. AIMS: This study aims to evaluate the Gal-1 expression in different clinical stages and histological grades of OSCC. SETTINGS AND DESIGN: Forty histopathologically diagnosed cases of OSCC, including 16 cases of well-differentiated, 18 moderately differentiated and 6 poorly differentiated carcinomas, were included in the study group. MATERIALS AND METHODS: The samples were subjected to staining using primary mouse monoclonal antibodies against Gal-1 and visualized using polymer-HRP detection system. STATISTICAL ANALYSIS: The nonparametric Mann-Whitney U-test and Kruskal-Wallis ANOVA test were used for the statistical analysis. RESULTS: Gal-1 expression was higher in advanced stages of OSCC, and the results were statistically significant. Immunoexpression of Gal-1 increased with advancing histological grades of OSCC with statistically significant results. CONCLUSION: Gal-1 plays an important role in invasion, metastasis and as a prognostic marker.

Extracellular matrix metalloproteinase inducer expression in histological grades of oral squamous cell carcinoma - An immunohistochemical study.

BACKGROUND: Oral squamous cell carcinoma (OSCC) is the most common type of head-and-neck cancer. It is a complex and relentless malignancy prone to local invasion and dissemination. An insight into the molecular alterations associated with metastasis will provide critical insights into the fundamental mechanisms underlying its progression and further contribute to improvements in the clinical management of H and N cancer patients. Hence, identifying specific biomarkers would pave the way for early detection and prognosis of OSCC. Extracellular matrix metalloproteinase inducer (EMMPRIN) is a membrane-bound glycoprotein found on the surface of tumor cells. It plays a central role in the promotion of tumor invasion, progression and metastasis as it upregulates matrix metalloproteinases secreted from adjacent fibroblasts. There is a paucity of studies on the expression of EMMPRIN in OSCC. OBJECTIVES: The aim is to assess the immunohistochemical expression of EMMPRIN in OSCC and to compare it with the clinicopathological parameters and histological grades of OSCC. MATERIALS AND METHODS: Thirty histopathologically diagnosed cases of OSCC were included in the study. The slides were immunohistochemically analyzed for EMMPRIN expression and correlated with the clinicopathological parameters and histological grades of OSCC. RESULTS: EMMPRIN expression was noted in all 30 cases of OSCC. Strong EMMPRIN expression was noted in the advanced clinical stages of OSCC. Higher histological grades of OSCC exhibited strong EMMPRIN expression. CONCLUSION: EMMPRIN overexpression indicates that this protein could be used as an important biological prognostic marker to identify high-risk OSCC patients.

Evaluation of density of tumor-associated macrophages using CD163 in histological grades of oral squamous cell carcinoma, an immunohistochemical study.

BACKGROUND: Macrophages account for 30%-50% of the total inflammatory cell population of ''tumor microenvironment'' that plays an important role in cancer metastasis. M2 macrophages are designated as tumor-associated macrophages (TAMs). They are known to orchestrate all the stages of tumor progression. CD163 is TAMs-M2-specific marker. AIMS: The aim of the study was to evaluate the role of TAMs using CD163 in different histological grades of oral squamous cell carcinoma (OSCC). SETTING AND DESIGN: Expression of CD 163 was investigated in 30 histopthologically diagnosed cases of OSCC. MATERIALS AND METHODS: Two sections of 4-µ thickness were stained with hematoxylin and eosin, CD163 (Cell Marque, USA). The expression of TAMs with CD163-positive cells was done by counting the number of macrophages in three high-power fields (×400), and the mean number of macrophages per HPF was evaluated. STATISTICAL ANALYSIS: The statistical analysis was performed using Statistical Software SPSS version 20.0. RESULTS: CD163 TAMs score increasing in higher tumor, node, metastasis stages with significant positive correlation. CONCLUSION: With higher histological grades, CD163 TAMs score increased. Thus, TAMs may be considered as an independent factor for determining the progression of the tumor. The immunotherapeutic approaches to control M2 TAM numbers could protect against progression to malignancy.

Crosstalk of Intercellular Signaling Pathways in the Generation of Midbrain Dopaminergic Neurons In Vivo and from Stem Cells.

Dopamine-synthesizing neurons located in the mammalian ventral midbrain are at the center stage of biomedical research due to their involvement in severe human neuropsychiatric and neurodegenerative disorders, most prominently Parkinson's Disease (PD). The induction of midbrain dopaminergic (mDA) neurons depends on two important signaling centers of the mammalian embryo: the ventral midline or floor plate (FP) of the neural tube, and the isthmic organizer (IsO) at the mid-/hindbrain boundary (MHB). Cells located within and close to the FP secrete sonic hedgehog (SHH), and members of the wingless-type MMTV integration site family (WNT1/5A), as well as bone morphogenetic protein (BMP) family. The IsO cells secrete WNT1 and the fibroblast growth factor 8 (FGF8). Accordingly, the FGF8, SHH, WNT, and BMP signaling pathways play crucial roles during the development of the mDA neurons in the mammalian embryo. Moreover, these morphogens are essential for the generation of stem cell-derived mDA neurons, which are critical for the modeling, drug screening, and cell replacement therapy of PD. This review summarizes our current knowledge about the functions and crosstalk of these signaling pathways in mammalian mDA neuron development in vivo and their applications in stem cell-based paradigms for the efficient derivation of these neurons in vitro.

BMP/SMAD Pathway Promotes Neurogenesis of Midbrain Dopaminergic Neurons In Vivo and in Human Induced Pluripotent and Neural Stem Cells.

The embryonic formation of midbrain dopaminergic (mDA) neurons in vivo provides critical guidelines for the in vitro differentiation of mDA neurons from stem cells, which are currently being developed for Parkinson's disease cell replacement therapy. Bone morphogenetic protein (BMP)/SMAD inhibition is routinely used during early steps of stem cell differentiation protocols, including for the generation of mDA neurons. However, the function of the BMP/SMAD pathway for in vivo specification of mammalian mDA neurons is virtually unknown. Here, we report that BMP5/7-deficient mice (Bmp5-/-; Bmp7-/-) lack mDA neurons due to reduced neurogenesis in the mDA progenitor domain. As molecular mechanisms accounting for these alterations in Bmp5-/-; Bmp7-/- mutants, we have identified expression changes of the BMP/SMAD target genes MSX1/2 (msh homeobox 1/2) and SHH (sonic hedgehog). Conditionally inactivating SMAD1 in neural stem cells of mice in vivo (Smad1Nes) hampered the differentiation of progenitor cells into mDA neurons by preventing cell cycle exit, especially of TH+SOX6+ (tyrosine hydroxylase, SRY-box 6) and TH+GIRK2+ (potassium voltage-gated channel subfamily-J member-6) substantia nigra neurons. BMP5/7 robustly increased the in vitro differentiation of human induced pluripotent stem cells and induced neural stem cells to mDA neurons by up to threefold. In conclusion, we have identified BMP/SMAD signaling as a novel critical pathway orchestrating essential steps of mammalian mDA neurogenesis in vivo that balances progenitor proliferation and differentiation. Moreover, we demonstrate the potential of BMPs to improve the generation of stem-cell-derived mDA neurons in vitro, highlighting the importance of sequential BMP/SMAD inhibition and activation in this process.SIGNIFICANCE STATEMENT We identify bone morphogenetic protein (BMP)/SMAD signaling as a novel essential pathway regulating the development of mammalian midbrain dopaminergic (mDA) neurons in vivo and provide insights into the molecular mechanisms of this process. BMP5/7 regulate MSX1/2 (msh homeobox 1/2) and SHH (sonic hedgehog) expression to direct mDA neurogenesis. Moreover, the BMP signaling component SMAD1 controls the differentiation of mDA progenitors, particularly to substantia nigra neurons, by directing their cell cycle exit. Importantly, BMP5/7 increase robustly the differentiation of human induced pluripotent and induced neural stem cells to mDA neurons. BMP/SMAD are routinely inhibited in initial stages of stem cell differentiation protocols currently being developed for Parkinson's disease cell replacement therapies. Therefore, our findings on opposing roles of the BMP/SMAD pathway during in vitro mDA neurogenesis might improve these procedures significantly.