Dedifferentiating initiation and embryogenesis from freshly-isolated microspores of barley

By using DNA-specific fluorescent dye and a confocal laser scanning microscope, the present study was designed to investigate the cytological characteristics of dedifferentiating initiation during pretreatment and em-bryogenesis during culture in freshly-isolated microspores of barley, and the difference in main developmental pathway between freshly-isolated and cold-treated microspores. The results revealed that ( i ) freshly-isolated microspores started the initiation within 12 h of mannitol pretreatment, whose main cytological characteristics were that: cell vol-ume was obviously extended; the volume of nuclei and nucleoli were also greatly increased; nucleoli were extremely clear and highly condensed; N/C ratio was very high; ( ii ) all the pretreatment methods led to the initiation of the mi-crospores, thus triggering the embryogenic process; ( iii ) pretreatment methods influenced the main developmental pathway of microspores by changing the pattern of the first mitosis. The cold-treated

Organoid-derived human retinal progenitor cells promote early dedifferentiation of Müller glia in Royal College of Surgeons rats

AIM:To explore whether the subretinal transplantation of retinal progenitor cells from human embryonic stem cell-derived retinal organoid(h ERO-RPCs)could promote Müller glia dedifferentiation and transdifferentiation,thus improving visual function and delaying retinal degenerative progression.METHODS:h ERO-RPCs were subretinally transplanted into Royal College of Surgeons(RCS)rats.Electroretinography(ERG)recording was performed at 4 and 8wk postoperation to assess retinal function.Using immunofluorescence,the changes in outer nuclear layer(ONL)thickness and retinal Müller glia were explored at 2,4,and 8wk postoperation.To verify the effect of h ERO-RPCs on Müller glia in vitro,we cocultured h ERO-RPCs with Müller glia with a Transwell system.After coculture,Ki67 staining and quantitative polymerase chain reaction(q PCR)were performed to measure the proliferation and m RNA levels of Müller glia respectively.Cell migration experiment was used to detect the effect of h ERO-RPCs on Müller glial migration.Comparisons between two groups were performed by the unpaired Student’s t-test,and comparisons among multiple groups were made with one-way ANOVA followed by Tukey’s multiple comparison test.RESULTS:The visual function and ONL thickness of RCS rats were significantly improved by transplantation of h ERO-RPCs at 4 and 8wk postoperation.In addition to inhibiting gliosis at 4 and 8wk postoperation,h ERO-RPCs significantly increased the expression of dedifferentiation-associated transcriptional factor in Müller glia and promoted the migration at 2,4 and 8wk postoperation,but not the transdifferentiation of these cells in RCS rats.In vitro,using the Transwell system,we found that h ERO-RPCs promoted the proliferation and migration of primary rat Müller glia and induced their dedifferentiation at the m RNA level.CONCLUSION:These results show that h ERO-RPCs might promote early dedifferentiation of Müller glia,which may provide novel insights into the mechanisms of stem cell therapy and Müller glial reprogramming,contributing to the development of novel therapies for retinal degeneration disorders.

Primary dedifferentiated chondrosarcoma of the lung with a 4-year history of breast cancer:A case report

BACKGROUND Primary dedifferentiated chondrosarcoma(DDCS)of the lung is extremely rare and has a poor prognosis,especially in patients with a history of carcinomas and related treatment.Herein,we report a case of primary DDCS of the lung in a patient with a 4-year history of breast cancer and related treatment.CASE SUMMARY A 49-year-old woman was admitted to our hospital with complaints of headache,dizziness,slurred speech,and dyskinesia in May 2021.Computed tomography(CT)examinations showed multiple nodules in the brain,vertebral body,and both lungs with multiple enlarged lymph nodes in the right hilum and mediastinum,which were considered metastases of breast cancer.No obvious mass was discovered in the right hilum.After several months of related administration,the patient's headache disappeared,and her condition improved.However,new problems of asthma,dyspnea,cough,and restricted activity appeared in late November 2021.Although the CT scan indicated that the lesions in the brain,lung,and vertebral body had shrunk or disappeared,a soft tissue density lesion appeared in her right hilum and blocked the bronchial lumen.To relieve her dyspnea,part of the mass was resected,and a stent was placed via fiberoptic bronchoscopy.Following a complete pathological examination of the tumor,it was confirmed to be a primary DDCS of the lung.The patient then received two rounds of systemic chemotherapy with a regimen of cisplatin+ifosfamide+doxorubicin hydrochloride liposome,palliative radiotherapy for the tumor in her right lung,and four cycles of systemic chemotherapy and targeted therapy with a regimen of temozolomide combined with bevacizumab successively.She was in stable condition after the completion of the systemic chemotherapy and targeted therapy but underwent rapid progression after lung radiotherapy.The CT examinations showed multiple nodules in the brain and in both lungs,and the tumor in the right hilum was increased in size.CONCLUSION This case revealed a rare primary DDCS of the lung with a medical history of breast cancer,meaning a worse prognosis and making it more difficult to treat.

Giant dedifferentiated liposarcoma of the gastrocolic ligament:A case report

BACKGROUND Dedifferentiated liposarcoma(DDLS)has a worse prognosis and occurs most commonly in the retroperitoneal region and rarely in the intraperitoneal region.Histological diagnosis was revolutionized by the combined contributions of histoimmuno-chemistry and molecular biology.Aside from surgery,there is no consensus on the optimal treatment for this chemoresistant cancer.CASE SUMMARY A thirty-year-old black female presented with a large painful abdominal mass occupying nearly the entire abdomen and progressive weight loss was admitted for surgery.Abdominal computed tomography showed a large heterogeneous mass of the mesentery that was sized 18 cm×16 cm in size and had heterogeneous contrast enhancement.During laparotomy,en bloc excision of the large and multilobulated gastrocolic ligament mass was performed.The initial postoperative histopathological diagnosis was undifferentiated sarcoma.Finally,the results of immunohistochemistry and molecular biology allowed us to confirm the diagnosis of DDLS.The tumour followed an aggressive evolution with diffuse metastasis,causing the death of the patient less than 5 mo after the operation.CONCLUSION Dedifferentiated liposarcomas are rare tumours that typically originate in the retroperitoneum but may arise in unexpected locations.

Dedifferentiated fat cells: an alternative source of adult multipotent cells from the adipose tissues

When adipose-derived stem cells （ASCs） arc retrieved from the stromal vascular portion of adipose tissue, a large amount of mature adipocytes are often discarded. However, by modified ceiling culture technique based on their buoyancy, mature adipocytes can be easily isolated from the adipose cell suspension and dediffercn- tiated into lipid-frce fibroblast-like cells, named dediffercntiated fat （DFAT） cells. DFAT cells rc-establish active proliferation ability and undertake multipotent capacities. Compared with ASCs and other adult stem cells, DFAT cells showed unique advantages in their abundance, isolation and homogeneity. In this concise review, the establishment and culture methods of DFAT cells arc introduced and the current profiles of their cellular nature are summarized. Under proper inducti~,n culture in vitro or environment in vivo, DFAT cells could demonstrate adipogenic, osteogenic, chondrogenie and myogenic potentials. In angiogenie conditions, DFAT cells could exhibit perivascular characteristics antt elicit neovascularization. Our preliminary findings also suggested the pericyte phenotype underlying such cell lineage, which supported a novel interpretation about the common origin of mesenchymal stem cells and tissue-specific stem cells within blood vessel walls. Current research on DFAT cells indicated that this alternative source of adult multipotent cells has great potential in tissue engineering and regenerative medicine.

Axon degeneration： make the Schwann cell great again

Axonal degeneration is a pivotal feature of many neurodegenerative conditions and substantially accounts for neurological morbidity. A widely used experimental model to study the mechanisms of axonal degeneration is Wallerian degeneration （WD）, which occurs after acute axonal injury. In the peripheral nervous system （PNS）, WD is characterized by swift dismantling and clearance of injured axons with their myelin sheaths. This is a prerequisite for successful axonal regeneration. In the central nervous system （CNS）, WD is much slower, which significantly contributes to failed axonal regeneration. Although it is well documented that Schwann cells （SCs） have a critical role in the regenerative potential of the PNS, to date we have only scarce knowledge as to how SCs ＇sense＇ axonal injury and immediately respond to it. In this regard, it remains unknown as to whether SCs play the role of a passive bystander or an active director during the execution of the highly orchestrated disintegration program of axons. Older reports, together with more recent studies, suggest that SCs mount dynamic injury responses minutes after axonal injury, long before axonal breakdown occurs. The swift SC response to axonal injury could play either a pro degenerative role, or alternatively a supportive role, to the integrity of distressed axons that have not yet committed to degenerate. Indeed, supporting the latter concept, recent 昀ndings in a chronic PNS neurodegeneration model indicate that deactivation of a key molecule promoting SC injury responses exacerbates axonal loss. If this holds true in a broader spectrum of conditions, it may provide the grounds for the development of new glia-centric therapeutic approaches to counteract axonal loss.

Activation of extracellular signal-related kinases 1 and 2 in Sertoli cells in experimentally cryptorchid rhesus monkeys

Aim： To assess the spatiotemporal changes in the expression of extracellular signal-regulated kinases 1 and 2 （ERK1/ 2）, c-Jun N-terminal kinases （JNK） and p38 mitogen-activated protein kinases （MAPK） in response to heat stress in the cryptorchid testis, and to investigate a possible relation to Sertoli cell dedifferentiation. Methods： Immunohistochemistry and western blot were used to examine the expression and activation of ERK1/2, p38 and JNK in the cryptorchid testis at various stages after experimental cryptorchidism. Results： The abdominal temperature did not obviously change the total ERK1/2 expression but significantly activated phospho-ERK1/2 in the Sertoli cells of the cryptorchid testis. Heat stress increased total JNK expression in the Sertoli cells of the cryptorchid testis but did not activate phospho-JNK. Neither total p38 nor phospho-p38 was induced by heat stress in the Sertoli cells of the cryptorchid testis. Changes in the spatiotemporal expression of cytokeratin 18 （CK18）, a marker of immature or undifferentiated Sertoli cells, were induced in the cryptorchid testis in a pattern similar to the activation of ERK1/2. Condusion： The activation of ERK1/2 in the testis may be related to dedifferentiation of Sertoli cells under heat stress induced by experimental cryptorchidism.

Dedifferentiated fat cells:A cell source for regenerative medicine

The identification of an ideal cell source for tissue regeneration remains a challenge in the stem cell field. The ability of progeny cells to differentiate into other cell types is important for the processes of tissue reconstruction and tissue engineering and has clinical, biochemical or molecular implications. The adaptation of stem cells from adipose tissue for use in regenerative medicine has created a new role for adipocytes. Mature adipocytes can easily be isolated from adipose cell suspensions and allowed to dedifferentiate into lipidfree multipotent cells, referred to as dedifferentiated fat(DFAT) cells. Compared to other adult stem cells, the DFAT cells have unique advantages in their abundance, ease of isolation and homogeneity. Under proper condition in vitro and in vivo, the DFAT cells have exhibited adipogenic, osteogenic, chondrogenic, cardiomyogenc, angiogenic, myogenic, and neurogenic potentials. In this review, we first discuss the phenomena of dedifferentiation and transdifferentiation of cells, and then dedifferentiation of adipocytes in particular. Understanding the dedifferentiation process itself may contribute to our knowledge of normal growth processes, as well as mechanisms of disease. Second, we highlight new developments in DFAT cell culture and summarize the current understanding of DFAT cell properties. The unique features of DFAT cells are promising for clinical applications such as tissue regeneration.

Segment boundaries of the adult rat epididymis limit interstitial signaling by potential paracrine factors and segments lose differential gene expression after efferent duct ligation

The epididymis is divided into caput, corpus and cauda regions, organized into intraregional segments separated by connective tissue septa （CTS）. In the adult rat and mouse these segments are highly differentiated. Regulation of these segments is by endocrine, lumicrine and paracrine factors, the relative importance of which remains under investigation. Here, the ability of the CTS to limit signaling in the interstitial compartment is reviewed as is the effect of 15 days of unilateral efferent duct ligation （EDL） on ipsilateral segmental transcriptional profiles. Inter-segmental microperifusions of epidermal growth factor （EGF）, vascular endothelial growth factor （VEGFA） and fibroblast growth factor 2 （FGF2） increased phosphorylation of mitogen activated protein kinase （MAPK） in segments 1 and 2 of the rat epididymis and the effects of all factors were limited by the CTS separating the segments. Microan＇ay analysis of segmental gene expression determined the effect of 15 days of unilateral EDL on the transcriptome-wide gene expression of rat segments 1-4. Over 11 000 genes were expressed in each of the four segments and over 2 000 transcripts in segment 1 responded to deprivation of testicular lumicrine factors. Segments 1 and 2 of control tissues were the most transcriptionally different and EDL had its greatest effects there. In the absence of lumicrine factors, all four segments regressed to a transcriptionally undifferentiated state, consistent with the less differentiated histology. Deprivation of lumicrine factors could stimulate an individual gene＇s expression in some segments yet suppress it in others. Such results reveal a higher complexity of the regulation of rat epididymal segments than that is generally appreciated. （Asian J Androl 2007 July; 9： 565-573）

Dedifferentiated liposarcoma of the small bowel mesentery presenting as a submucosal mass

Dedifferentiated liposarcoma(DDLPS) is a variant of liposarcoma but with a more aggressive course.It occurs most commonly in the retroperitoneum and rarely in any other anatomical location.We describe a case of DDLPS arising from the small bowel mesentery presenting as submucosal mass of the small bowel.The current case is unusual as the tumor originated from the small bowel mesentery and a dedifferentiated component transmurally invaded the small bowel wall,including the small bowel submucosa.

Pancreatic β cell regeneration induced by clinical and preclinical agents

Diabetes,one of the most common chronic diseases in the modern world,has pancreaticβcell deficiency as a major part of its pathophysiological mechanism.Pancreatic regeneration is a potential therapeutic strategy for the recovery ofβcell loss.However,endocrine islets have limited regenerative capacity,especially in adult humans.Almost all hypoglycemic drugs can protectβcells by inhibitingβcell apoptosis and dedifferentiation via correction of hyperglycemia and amelioration of the consequent inflammation and oxidative stress.Several agents,including glucagon-like peptide-1 andγ-aminobutyric acid,have been shown to promoteβcell proliferation,which is considered the main source of the regeneratedβcells in adult rodents,but with less clarity in humans.Pancreatic progenitor cells might exist and be activated under particular circumstances.Artemisinins andγ-aminobutyric acid can induceα-to-βcell conversion,although some disputes exist.Intestinal endocrine progenitors can transdeterminate into insulin-producing cells in the gut after FoxO1 deletion,and pharmacological research into FoxO1 inhibition is ongoing.Other cells,including pancreatic acinar cells,can transdifferentiate intoβcells,and clinical and preclinical strategies are currently underway.In this review,we summarize the clinical and preclinical agents used in different approaches forβcell regeneration and make some suggestions regarding future perspectives for clinical application.

Two faces of Schwann cell dedifferentiation in peripheral neurodegenerative diseases:pro-demyelinating and axon-preservative functions

Schwann cells are glial cells that are responsible for the synthesis and maintenance of the myelin sheath in the peripheral nerve system. Under pathological conditions, such as physical nerve injury and inflammatory neuropathies, Schwann cells undergo a substantial phenotype transformation that is not related to their intended function. For example, Schwann cells dedifferentiate into immature states and thereby cease to express myelin genes after nerve injury.

Adult neurogenesis from reprogrammed astrocytes

The details of adult neurogenesis,including environmental triggers,region specificity,and species homology remain an area of intense investigation.Slowing or halting age-related cognitive dysfunction,or restoring neurons lost to disease or injury represent just a fraction of potential therapeutic applications.New neurons can derive from stem cells,pluripotent neural progenitor cells,or non-neuronal glial cells,such as astrocytes.Astrocytes must be epigenetically"reprogrammed"to become neurons,which can occur both naturally in vivo,and via artificial exogenous treatments.While neural progenitor cells are localized to a few neurogenic zones in the adult brain,astrocytes populate almost every brain structure.In this review,we will summarize recent research into neurogenesis that arises from conversion of post-mitotic astrocytes,detail the genetic and epigenetic pathways that regulate this process,and discuss the possible clinical relevance in supplementing stem-cell neurogenic therapies.

Thoracoscopic resection of a huge esophageal dedifferentiated liposarcoma: A case report

BACKGROUND Esophageal liposarcoma is a rare malignant tumor and an esophageal dedifferentiated liposarcoma(DDL)is extremely rare.There are no reports on the treatment of DDL by thoracoscopic surgery.CASE SUMMARY A 38-year-old woman presented with dysphagia and dyspnea.Imaging examination showed a large mass in the posterior mediastinum.The patient also developed respiratory failure and it was unclear whether this was caused by a mass from inside or outside the esophagus.We decided to perform thoracoscopic exploration to relieve the obstruction caused by tracheal compression.The upper segment of the esophagus was split longitudinally,and most of the mass could be removed from the esophageal lumen to the thoracic cavity.The pedicle was excised by linear cutting closers under mirrors.Little residual mass was visualized by gastroscopy.The mucous and muscular layers were closed by interrupted sutures.Pathological examination showed that the mass was a DDL.The patient did not have any dysphagia or dyspnea 2 wk postoperatively and refused any further treatment.Computed tomography and esophagoscopy did not find any recurrence at up to 20 mo postoperatively.CONCLUSION Thoracoscopy can be used to treat large esophageal masses.

Nanog overexpression allows human mesenchymal stem cells to differentiate into neural cells——Nanog transdifferentiates mesenchymal stem cells

Although stem cell therapies have been proposed as a candidate for treating neurological diseases, the best stem cell source and their therapeutic efficacy remain uncertain. Embryonic stem cells (ESCs) can efficiently generate multiple cell types, but pose ethical and clinical challenges, while the more accessible adult stem cells have a limited develop-mental potential. Following included-expression of Nanog, an ESC gene, adult human mesenchymal stem cells (HMSCs) are able to develop into cells exhibiting neural cell-like characteristics based on morphology, cell markers, and gene expressions. After expansion, Nanog overexpressed HMSCs differentiated into cells immunopositive for betaIII-tubulin and glial fibrillary acidic protein, lineage markers for neurons and astrocytes, respectively, under the influence of con-ditional media from differentiated human neural stem cells. This result indicates that the Nanog expression increased the ability of HMSCs to become a neural cell lineage. We further demonstrated that Nanog-overexpressed HMSCs were able to survive, migrate, and undergo neural cell-like differentiation after transplantation in vivo. This data offers an exciting prospect that peripheral adult stem cells can be modified and used to treat neurological diseases.

miR-30c promotes Schwann cell remyelination following peripheral nerve injury

Differential expression of mi RNAs occurs in injured proximal nerve stumps and includes mi RNAs that are firstly down-regulated and then gradually up-regulated following nerve injury.These mi RNAs might be related to a Schwann cell phenotypic switch.mi R-30 c,as a member of this group,was further investigated in the current study.Sprague-Dawley rats underwent sciatic nerve transection and proximal nerve stumps were collected at 1,4,7,14,21,and 28 days post injury for analysis.Following sciatic nerve injury,mi R-30 c was down-regulated,reaching a minimum on day 4,and was then upregulated to normal levels.Schwann cells were isolated from neonatal rat sciatic nerve stumps,then transfected with mi R-30 c agomir and co-cultured in vitro with dorsal root ganglia.The enhanced expression of mi R-30 c robustly increased the amount of myelin-associated protein in the co-cultured dorsal root ganglia and Schwann cells.We then modeled sciatic nerve crush injury in vivo in Sprague-Dawley rats and tested the effect of perineural injection of mi R-30 c agomir on myelin sheath regeneration.Fourteen days after surgery,sciatic nerve stumps were harvested and subjected to immunohistochemistry,western blot analysis,and transmission electron microscopy.The direct injection of mi R-30 c stimulated the formation of myelin sheath,thus contributing to peripheral nerve regeneration.Overall,our findings indicate that mi R-30 c can promote Schwann cell myelination following peripheral nerve injury.The functional study of mi R-30 c will benefit the discovery of new therapeutic targets and the development of new treatment strategies for peripheral nerve regeneration.

Adipose tissue in bone regeneration-stem cell source and beyond

Adipose tissue(AT)is recognized as a complex organ involved in major homeostatic body functions,such as food intake,energy balance,immunomodulation,development and growth,and functioning of the reproductive organs.The role of AT in tissue and organ homeostasis,repair and regeneration is increasingly recognized.Different AT compartments(white AT,brown AT and bone marrow AT)and their interrelation with bone metabolism will be presented.AT-derived stem cell populations-adipose-derived mesenchymal stem cells and pluripotentlike stem cells.Multilineage differentiating stress-enduring and dedifferentiated fat cells can be obtained in relatively high quantities compared to other sources.Their role in different strategies of bone and fracture healing tissue engineering and cell therapy will be described.The current use of AT-or AT-derived stem cell populations for fracture healing and bone regenerative strategies will be presented,as well as major challenges in furthering bone regenerative strategies to clinical settings.

Temporal Integrative Omics Reveals an Increase in Nondegradative Ubiquitylation during Primary Hepatocyte Dedifferentiation

Primary hepatocytes(PHCs)are widely used in various fields,but the progressive deterioration of liverspecific features in vitro significantly limits their application.While the transcriptional regulation and whole cell proteome(WCP)of PHCs have been extensively studied,only a small number of studies have addressed the role of posttranslational modifications in this process.To elucidate the underlying mechanisms that induce dedifferentiation,we carried out parallel quantifications of the transcriptome,WCP,ubiquitinome,and phosphoproteome of rat PHCs after 0,6,12,24,and 48 h of in vitro culture.Our data constitute a detailed proteomic analysis of dedifferentiated PHCs including 2196 proteins,2056 ubiquitinated sites,and 4932 phosphorylated peptides.We revealed a low correlation between the transcriptome and WCP during dedifferentiation.A combined analysis of the ubiquitinome with the corresponding WCP indicated that the dedifferentiation of PHCs led to an increase in nondegradative K27 ubiquitination.Functional analysis of the altered phosphoproteins suggested a significant enrichment in ferroptosis.In all,404 proteins with both ubiquitination and phosphorylation were identified to be involved in critical metabolic events.Furthermore,Ptbph Hnqjd,Hnrnpu,and Srrm2 were identified as hub genes.Taken together,our data provide new insights into proteome dynamics during PHC dedifferentiation and potential targets to inhibit the dedifferentiation process.

Primary gastric dedifferentiated liposarcoma resected endoscopically:A case report

BACKGROUND Liposarcoma is one of the most common adult mesenchymal tumors but is uncommon in the gastrointestinal tract and extremely rare in the stomach.Furthermore,the histological subtypes of liposarcoma usually reported in the stomach are well-differentiated or myxoid,and few reports have been issued on small-sized gastric liposarcomas resected endoscopically and followed up.Herein,we report a case of primary gastric dedifferentiated liposarcoma(DL)that was resected endoscopically.CASE SUMMARY A 67-year-old female Korean patient was referred to our institution for further evaluation of a gastric submucosal tumor(SMT)located in the lesser curvature of the gastric body by esophagogastroduodenoscopy.Endoscopic ultrasound revealed a well-circumscribed,slightly heterogeneous,isoechoic,17 mm×10 mm sized mass originating from the third sonographic layer.Computed tomography showed no evidence of significant lymph node enlargement or distant metastasis.Endoscopic resection was undertaken using the snare resection technique after mucosal precutting to provide a definitive histopathologic diagnosis,which proved to be consistent with DL,based on its morphology and the immunoexpressions of MDM2 and CDK4.The patient was planned for surgery because the deep resection margin was positive for malignancy.After declining any invasive procedure or adjuvant treatment,the patient was placed under close follow-up,and at one year after endoscopic resection,remained disease free.CONCLUSION This is the first reported case of a small primary gastric DL resected endoscopically and followed up.This report demonstrates that when diagnosis of a SMT is uncertain,the use of invasive techniques,including endoscopic resection,should be considered.

Dedifferentiated chondrosarcoma of the middle finger arising from a solitary enchondroma:A case report

BACKGROUND Dedifferentiated chondrosarcoma(DDCS)accounts for 10%of all chondrosarcomas and has the poorest outcome,with a 5-year survival rate of 7%-25%.DDCS commonly occurs in the femur and pelvis,whereas DDCS of the finger is extremely rare.Furthermore,the histological findings of preexisting solitary enchondroma samples are important and valuable for diagnosing malignant transformations.CASE SUMMARY We report our experience with DDCS in the proximal phalanx of the left middle finger of an 87-year-old woman.She had undergone surgery for enchondroma,with curettage and artificial bone grafting,11 years ago,in the same location.Several years after the primary surgery,the left middle finger gradually started to enlarge,and the growth speed increased in the past year.Plain radiographs showed an expansive osteolytic lesion with calcifications and residual grafting material.Owing to the suspicion of malignancy,we performed ray amputation.Histological findings revealed an abrupt transition between the low-grade chondrosarcoma and dedifferentiated sarcoma components.The dedifferentiated components showed the features of a high-grade undifferentiated pleomorphic sarcoma.The patient was diagnosed with DDCS arising from a preexisting enchondroma.She had no local recurrence or distant metastasis and died of pneumonia 6 years and 10 months after the second surgery.CONCLUSION The histological findings of a precursor lesion showed a typical enchondroma,suggesting that DDCS can arise from enchondroma.