Intrinsic Immunity Shapes Viral Resistance of Stem Cells.

Stem cells are highly resistant to viral infection compared to their differentiated progeny; however, the mechanism is mysterious. Here, we analyzed gene expression in mammalian stem cells and cells at various stages of differentiation. We find that, conserved across species, stem cells express a subset of genes previously classified as interferon (IFN) stimulated genes (ISGs) but that expression is intrinsic, as stem cells are refractory to interferon. This intrinsic ISG expression varies in a cell-type-specific manner, and many ISGs decrease upon differentiation, at which time cells become IFN responsive, allowing induction of a broad spectrum of ISGs by IFN signaling. Importantly, we show that intrinsically expressed ISGs protect stem cells against viral infection. We demonstrate the in vivo importance of intrinsic ISG expression for protecting stem cells and their differentiation potential during viral infection. These findings have intriguing implications for understanding stem cell biology and the evolution of pathogen resistance.

Heat shock protein 101 contributes to the thermotolerance of male meiosis in maize.

High temperatures interfere with meiotic recombination and the subsequent progression of meiosis in plants, but few genes involved in meiotic thermotolerance have been characterized. Here, we characterize a maize (Zea mays) classic dominant male-sterile mutant Ms42, which has defects in pairing and synapsis of homologous chromosomes and DNA double-strand break (DSB) repair. Ms42 encodes a member of the heat shock protein family, HSP101, which accumulates in pollen mother cells. Analysis of the dominant Ms42 mutant and hsp101 null mutants reveals that HSP101 functions in RADIATION SENSITIVE 51 loading, DSB repair, and subsequent meiosis. Consistent with these functions, overexpression of Hsp101 in anthers results in robust microspores with enhanced heat tolerance. These results demonstrate that HSP101 mediates thermotolerance during microsporogenesis, shedding light on the genetic basis underlying the adaptation of male meiocytes to high temperatures.

Transcriptome and small RNA analysis unveils novel insights into the C4 gene regulation in sugarcane.

MAIN CONCLUSION: This study reveals miRNA indirect regulation of C4 genes in sugarcane through transcription factors, highlighting potential key regulators like SsHAM3a. C4 photosynthesis is crucial for the high productivity and biomass of sugarcane, however, the miRNA regulation of C4 genes in sugarcane remains elusive. We have identified 384 miRNAs along the leaf gradients, including 293 known miRNAs and 91 novel miRNAs. Among these, 86 unique miRNAs exhibited differential expression patterns, and we identified 3511 potential expressed targets of these differentially expressed miRNAs (DEmiRNAs). Analyses using Pearson correlation coefficient (PCC) and Gene Ontology (GO) enrichment revealed that targets of miRNAs with positive correlations are integral to chlorophyll-related photosynthetic processes. In contrast, negatively correlated pairs are primarily associated with metabolic functions. It is worth noting that no C4 genes were predicted as targets of DEmiRNAs. Our application of weighted gene co-expression network analysis (WGCNA) led to a gene regulatory network (GRN) suggesting miRNAs might indirectly regulate C4 genes via transcription factors (TFs). The GRAS TF SsHAM3a emerged as a potential regulator of C4 genes, targeted by miR171y and miR171am, and exhibiting a negative correlation with miRNA expression along the leaf gradient. This study sheds light on the complex involvement of miRNAs in regulating C4 genes, offering a foundation for future research into enhancing sugarcane's photosynthetic efficiency.

Rapamycin antagonizes angiogenesis and lymphangiogenesis through myeloid-derived suppressor cells in corneal transplantation.

Rapamycin is an immunosuppressive drug that is widely used in the postsurgery management of transplantation. To date, the mechanism by which rapamycin reduces posttransplant neovascularization has not been fully understood. Given the original avascularity and immune privilege of the cornea, corneal transplantation is considered as an ideal model to investigate neovascularization and its effects on allograft rejection. Previously, we found that myeloid-derived suppressor cells (MDSC) prolong corneal allograft survival through suppression of angiogenesis and lymphangiogenesis. Here, we show that depletion of MDSC abolished rapamycin-mediated suppression of neovascularization and elongation of corneal allograft survival. RNA-sequencing analysis revealed that rapamycin dramatically enhanced the expression of arginase 1 (Arg1). Furthermore, an Arg1 inhibitor also completely abolished the rapamycin-mediated beneficial effects after corneal transplantation. Taken together, these findings indicate that MDSC and elevated Arg1 activity are essential for the immunosuppressive and antiangiogenic functions of rapamycin.

A marked elevation in serum creatinine/cystatin C ratio may indicate pseudo-acute kidney injury due to urinary ascites: a case report and literature review.

BACKGROUND: Urinary ascites represents a scarcely observed pseudo-acute kidney injury in clinical settings. Protracted or missed diagnosis may hold grave ramifications for patient outcomes. CASE PRESENTATION: We reported a case involving an elderly female patient experiencing pseudo-acute kidney injury accompanied by ascites, wherein her renal dysfunction persisted despite medical intervention and hemodialysis. Urinary ascites was identified via a methylene blue test and by contrasting creatinine levels in serum and ascites. This patient's kidney function was multiple typified by a marked elevation in serum creatinine/Cystatin C ratio (> 2 L/dL), potentially serving as a clue for the clinical diagnosis of pseudo-acute kidney injury engendered by urinary ascites. CONCLUSIONS: This case suggested the potential diagnostic value of an asynchronous increase in serum creatinine and serum CysC (or an increased ratio of blood creatinine to blood CysC) in patients with pseudo-acute kidney injury.

Kinkéliba (Combretum micranthum) Leaf Extract Alleviates Skin Inflammation: In Vitro and In Vivo Study.

Kinkéliba (Combretum micranthum, Seh-Haw in Wolof) is a popular bush tea in West African countries. Although the kinkéliba plant's leaves have been widely consumed for its nutritional and medicinal properties, its benefits on skin health potential have been practically untouched. In human epidermal primary keratinocytes, vitexin and isovitexin-rich kinkéliba extract treatment significantly (p < 0.001) enhanced up to 39.6% of the cell survival rate decreased by UV radiation irritation. The treatment of kinkéliba leaf extracts also reduced the production of UV-induced pro-inflammatory cytokines IL-6 and IL-8 by 57.6% and 42.5%, respectively (p < 0.001), which cause skin redness and skin barrier dysfunction, as well as wrinkles and collagen degradation. The anti-inflammation efficacy of kinkéliba leaf extracts might involve significant inhibition on the levels of cellular reactive oxygen species (ROS) (-70.8%, p < 0.001) and nitrotyrosine (-56.9%, p < 0.05). Further topical applications of kinkéliba leaf extract gel were found to reduce sodium lauryl sulfate (SLS)-induced skin inflammation: at D7, the skin trans-epidermal water loss (TEWL) and skin redness (a* value) were both reduced by 59.81% (p < 0.001) and 22.4% (p < 0.001), compared with D0. In vitro and in vivo data support a new topical application of the kinkéliba leaf as an effective active ingredient for the treatment of skin inflammation, as well as subsequent barrier dysfunction and inflammaging.

Natural variation of the BRD2 allele affects plant height and grain size in rice.

MAIN CONCLUSION: The zqdm1 identified from a rice mutant is a novel allele of BRD2 and is responsible for regulating rice plant height, grain size and appearance, which has possibilities on improving rice quality. Plant height is an important agronomic trait related to rice yield, and grain size directly determines grain yield in rice (Oryza sativa L.). With the development of molecular biotechnology and genome sequencing technology, more and more key genes associated with plant height and grain size have been cloned and identified in recent years. This study identified the zqdm1 gene from a mutant with reduced plant height and grain size. The zqdm1 gene was revealed to be a new allele of BRASSINOSTEROID DEFICIENT DWARF 2 (BRD2), encoding a FAD-linked oxidoreductase protein involved in the brassinosteroid (BR) biosynthesis pathway, and regulates plant height by reducing cell number of longitudinal sections of the internode and regulates grain size by altering cell expansion. A 369-bp DNA fragment was found inserted at the first exon, resulting in protein-coding termination. This mutation has not been discovered in previous studies. Complementation tests have confirmed that 369-bp insertion in BRD2 was responsible for the plant height and grain size changing in the zqdm1 mutant. Over-expression of BRD2 driven by different promoters into indica rice variety Jiafuzhan (JFZ) results in slender grains, suggesting its function on regulating grain shape. In summary, the current study has identified a new BRD2 allele, which facilitated the further research on the molecular mechanism of this gene on regulating growth and development.

Maize cytosolic invertase INVAN6 ensures faithful meiotic progression under heat stress.

Faithful meiotic progression ensures the generation of viable gametes. Studies suggested the male meiosis of plants is sensitive to ambient temperature, but the underlying molecular mechanisms remain elusive. Here, we characterized a maize (Zea mays ssp. mays L.) dominant male sterile mutant Mei025, in which the meiotic process of pollen mother cells (PMCs) was arrested after pachytene. An Asp-to-Asn replacement at position 276 of INVERTASE ALKALINE NEUTRAL 6 (INVAN6), a cytosolic invertase (CIN) that predominantly exists in PMCs and specifically hydrolyses sucrose, was revealed to cause meiotic defects in Mei025. INVAN6 interacts with itself as well as with four other CINs and seven 14-3-3 proteins. Although INVAN6Mei025 , the variant of INVAN6 found in Mei025, lacks hydrolytic activity entirely, its presence is deleterious to male meiosis, possibly in a dominant negative repression manner through interacting with its partner proteins. Notably, heat stress aggravated meiotic defects in invan6 null mutant. Further transcriptome data suggest INVAN6 has a fundamental role for sugar homeostasis and stress tolerance of male meiocytes. In summary, this work uncovered the function of maize CIN in male meiosis and revealed the role of CIN-mediated sugar metabolism and signalling in meiotic progression under heat stress.

Male sterile 28 encodes an ARGONAUTE family protein essential for male fertility in maize.

Male sterility is a common biological phenomenon in plants and is a useful trait for hybrid seed production. Normal tapetum development is essential for viable pollen generation. Although many genes involved in tapetum differentiation and degradation have been isolated in maize, elements that regulate tapetum development during pollen mother cell (PMC) meiosis are less studied. Here, we characterized a classical male-sterile mutant male sterile 28 (ms28) in maize. The ms28 mutant had a regular male meiosis process, while its tapetum cells showed premature vacuolation at the early meiotic prophase stage. Using map-based cloning, we cloned the Ms28 gene and confirmed its role in male fertility in maize together with two allelic mutants. Ms28 encodes the ARGONAUTE (AGO) family protein ZmAGO5c, and its transcripts primarily accumulate in premeiosis anthers, with more intense signals in PMCs. Transcriptomic analysis revealed that genes related to anther development, cell division, and reproductive structure development processes were differentially expressed between the ms28 mutant and its fertile siblings. Moreover, small RNA (sRNA) sequencing revealed that the small interfering RNA (siRNA) and microRNA (miRNA) abundances were obviously changed in ms28 meiotic anthers, which indicated that Ms28 may regulate tapetal cell development through small RNA-mediated epigenetic regulatory pathways. Taken together, our results shed more light on the functional mechanisms of the early development of the tapetum for male fertility in maize.

Biocompatibility and Biological Performance of Additive-Manufactured Bioabsorbable Iron-Based Porous Interference Screws in a Rabbit Model: A 1-Year Observational Study.

This study evaluated the mid-term (12-month) biomechanical, biocompatibility, and biological performance of additive-manufactured bioabsorbable iron-based interference screws (ISs). Two bioabsorbable iron IS types-manufactured using pure iron powder (iron_IS) and using pure iron powder with 0.2 wt% tricalcium phosphate (TCP_IS)-were compared with conventional metallic IS (control) using in vitro biocompatibility and degradation analyses and an in vivo animal study. The in vitro ultimate failure strength was significantly higher for iron_IS and TCP_IS than for control ISs at 3 months post-operatively; however, the difference between groups were nonsignificant thereafter. Moreover, at 3 months after implantation, iron_IS and TCP_IS increased bone volume fraction, bone surface area fraction, and percent intersection surface; the changes thereafter were nonsignificant. Iron_IS and TCP_IS demonstrated degradation over time with increased implant surface, decreased implant volume, and structure thickness; nevertheless, the analyses of visceral organs and biochemistry demonstrated normal results, except for time-dependent iron deposition in the spleen. Therefore, compared with conventional ISs, bioabsorbable iron-based ISs exhibit higher initial mechanical strength. Although iron-based ISs demonstrate high biocompatibility 12 months after implantation, their corrosive iron products may accumulate in the spleen. Because they demonstrate mechanical superiority along with considerable absorption capability after implantation, iron-based ISs may have potential applications in implantable medical-device development in the future.

A Missense Mutation in a Large Subunit of Ribonucleotide Reductase Confers Temperature-Gated Tassel Formation.

Temperature is a major factor regulating plant growth. To reproduce at extreme temperatures, plants must develop normal reproductive organs when exposed to temperature changes. However, little is known about the underlying molecular mechanisms. Here, we identified the maize (Zea mays) mutant thermosensitive vanishing tassel1-R (tvt1-R), which lacks tassels at high (restrictive) temperatures due to shoot apical meristem (SAM) arrest, but forms normal tassels at moderate (permissive) temperatures. The critical stage for phenotypic conversion in tvt1-R mutants is V2 to V6 (Vn, where "n" is the number of leaves with collars visible). Positional cloning and allelism and complementation tests revealed that a G-to-A mutation causing a Arg277-to-His277 substitution in ZmRNRL1, a ribonucleotide reductase (RNR) large subunit (RNRL), confers the tvt1-R mutant phenotype. RNR regulates the rate of deoxyribonucleoside triphosphate (dNTP) production for DNA replication and damage repair. By expression, yeast two-hybrid, RNA sequencing, and flow cytometric analyses, we found that ZmRNRL1-tvt1-R failed to interact with all three RNR small subunits at 34°C due to the Arg277-to-His277 substitution, which could impede RNR holoenzyme (α2ß2) formation, thereby decreasing the dNTP supply for DNA replication. Decreased dNTP supply may be especially severe for the SAM that requires a continuous, sufficient dNTP supply for rapid division, as demonstrated by the SAM arrest and tassel absence in tvt1-R mutants at restrictive temperatures. Our study reveals a novel mechanism of temperature-gated tassel formation in maize and provides insight into the role of RNRL in SAM maintenance.

Identification and transcriptome analysis of erythroblastic island macrophages.

The erythroblastic island (EBI), composed of a central macrophage and surrounding erythroid cells, was the first hematopoietic niche discovered. The identity of EBI macrophages has thus far remained elusive. Given that Epo is essential for erythropoiesis and that Epor is expressed in numerous nonerythroid cells, we hypothesized that EBI macrophages express Epor so that Epo can act on both erythroid cells and EBI macrophages simultaneously to ensure efficient erythropoiesis. To test this notion, we used Epor-eGFPcre knockin mouse model. We show that in bone marrow (BM) and fetal liver, a subset of macrophages express Epor-eGFP. Imaging flow cytometry analyses revealed that >90% of native EBIs comprised F4/80+Epor-eGFP+ macrophages. Human fetal liver EBIs also comprised EPOR+ macrophages. Gene expression profiles of BM F4/80+Epor-eGFP+ macrophages suggest a specialized function in supporting erythropoiesis. Molecules known to be important for EBI macrophage function such as Vcam1, CD169, Mertk, and Dnase2α were highly expressed in F4/80+Epor-eGFP+ macrophages compared with F4/80+Epor-eGFP- macrophages. Key molecules involved in iron recycling were also highly expressed in BM F4/80+Epor-eGFP+ macrophages, suggesting that EBI macrophages may provide an iron source for erythropoiesis within this niche. Thus, we have characterized EBI macrophages in mouse and man. Our findings provide important resources for future studies of EBI macrophage function during normal as well as disordered erythropoiesis in hematologic diseases such as thalassemia, polycythemia vera, and myelodysplastic syndromes.

Long-term outcomes of metabolic surgery in overweight and obese patients with type 2 diabetes in Asia.

AIM: To assess the outcomes of metabolic surgery in overweight and obese patients in Asia with type 2 diabetes (T2D). MATERIALS AND METHODS: The treatment outcomes of 1999 patients from the Asian Diabetes Surgery Summit database were analysed. The changes in treatment effects across time were assessed with respect to the surgical procedures performed by using generalized estimating equations. RESULTS: The most commonly performed procedure was the single-anastomosis gastric bypass (32.6%). Weight (from 106.2 ± 25.1 to 77.9 ± 18.8 kg), body mass index (BMI; from 38.7 ± 7.9 to 28.5 ± 5.9 kg/m2 ), blood sugar (from 9.3 ± 4.1 to 5.7 ± 1.8 mmol/L) and HbA1c (from 8.4% ± 1.8% to 6.0% ± 1.1%) significantly improved from baseline to 1 year (P < .001) and remained stable at 5 years (weight, 86.3 ± 23.3 kg; BMI, 31.7 ± 7.9 kg/m2 ; blood sugar, 5.8 ± 1.8 mmol/L, and HbA1c, 6.4% ± 1.2%; all P < .001 vs. baseline). Blood pressure and most lipid disorders also improved significantly. Of the treatment procedures, single-anastomosis gastric bypass had the most satisfactory outcomes with statistical significance for most disorders, whereas adjustable gastric banding displayed the least satisfactory outcomes. CONCLUSIONS: Metabolic surgery remarkably improved body weight, T2D and other metabolic disorders in Asian patients. However, the efficacy of individual procedures varied substantially.

Identified the novel resistant biomarkers for taxane-based therapy for triple-negative breast cancer.

Developing treatment strategies for triple-negative breast cancer (TNBC) has become an important clinical challenge. Currently, taxane-based chemotherapy is one of the standard treatments for TNBC. However, determining the key factor of taxane-resistance is urgently in need for clinical treatment for breast cancer. We used GEO data to generate paclitaxel resistance in two basal-like TNBC cell lines (SUM149 and MDA-MB-468). Seventy-one common upregulated differentially expressed genes (DEGs) and 11 downregulated DEGs were found to be related to paclitaxel resistance. By constructing protein-protein interactions, 28 hub proteins with a degree cutoff criterion of ≥1 were found. Nine hub genes (COL4A6, COL4A5, IL6, PDGFA, LPAR1, FYB, IL20, IL18R1 and INHBA) are involved in important signaling pathways. We found that upregulated PDGFA and downregulated COL4A6 were significantly associated with an insensitive response to neoadjuvant paclitaxel-based therapy. A Kaplan-Meier plot was created to check the prognostic values of 11 hub DEGs in terms of recurrence-free survival. High expressions of PDGFA and LAMB3 were correlated with poor recurrence-free survival, while low levels of FYB, IL18R1, and RASGRP1 indicated poorer relapse-free survival. Our results suggest that PDGFA, COL4A6, LPAR1, FYB, COL4A5, and RASGRP1 might be candidate target genes for taxane-based therapy in basal-like TNBC.

Biocompatibility and Biological Performance Evaluation of Additive-Manufactured Bioabsorbable Iron-Based Porous Suture Anchor in a Rabbit Model.

This study evaluated the biocompatibility and biological performance of novel additive-manufactured bioabsorbable iron-based porous suture anchors (iron_SAs). Two types of bioabsorbable iron_SAs, with double- and triple-helical structures (iron_SA_2_helix and iron_SA_3_helix, respectively), were compared with the synthetic polymer-based bioabsorbable suture anchor (polymer_SAs). An in vitro mechanical test, MTT assay, and scanning electron microscope (SEM) analysis were performed. An in vivo animal study was also performed. The three types of suture anchors were randomly implanted in the outer cortex of the lateral femoral condyle. The ultimate in vitro pullout strength of the iron_SA_3_helix group was significantly higher than the iron_SA_2_helix and polymer_SA groups. The MTT assay findings demonstrated no significant cytotoxicity, and the SEM analysis showed cells attachment on implant surface. The ultimate failure load of the iron_SA_3_helix group was significantly higher than that of the polymer_SA group. The micro-CT analysis indicated the iron_SA_3_helix group showed a higher bone volume fraction (BV/TV) after surgery. Moreover, both iron SAs underwent degradation with time. Iron_SAs with triple-helical threads and a porous structure demonstrated better mechanical strength and high biocompatibility after short-term implantation. The combined advantages of the mechanical superiority of the iron metal and the possibility of absorption after implantation make the iron_SA a suitable candidate for further development.

dlf1 promotes floral transition by directly activating ZmMADS4 and ZmMADS67 in the maize shoot apex.

The floral transition of the maize (Zea mays ssp. mays) shoot apical meristem determines leaf number and flowering time, which are key traits influencing local adaptation and yield potential. dlf1 (delayed flowering1) encodes a basic leucine zipper protein that interacts with the florigen ZCN8 to mediate floral induction in the shoot apex. However, the mechanism of how dlf1 promotes floral transition remains largely unknown. We demonstrate that dlf1 underlies qLB7-1, a quantitative trait locus controlling leaf number and flowering time that was identified in a BC2 S3 population derived from a cross between maize and its wild ancestor, teosinte (Zea mays ssp. parviglumis). Transcriptome sequencing and chromatin immunoprecipitation sequencing demonstrated that DLF1 binds the core promoter of two AP1/FUL subfamily MADS-box genes, ZmMADS4 and ZmMADS67, to activate their expression. Knocking out ZmMADS4 and ZmMADS67 both increased leaf number and delayed flowering, indicating that they promote the floral transition. Nucleotide diversity analysis revealed that dlf1 and ZmMADS67 were targeted by selection, suggesting that they may have played important roles in maize flowering time adaptation. We show that dlf1 promotes maize floral transition by directly activating ZmMADS4 and ZmMADS67 in the shoot apex, providing novel insights into the mechanism of maize floral transition.

TET2 deficiency leads to stem cell factor-dependent clonal expansion of dysfunctional erythroid progenitors.

Myelodysplastic syndromes (MDSs) are clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis. Anemia is the defining cytopenia of MDS patients, yet the molecular mechanisms for dyserythropoiesis in MDSs remain to be fully defined. Recent studies have revealed that heterozygous loss-of-function mutation of DNA dioxygenase TET2 is 1 of the most common mutations in MDSs and that TET2 deficiency disturbs erythroid differentiation. However, mechanistic insights into the role of TET2 on disordered erythropoiesis are not fully defined. Here, we show that TET2 deficiency leads initially to stem cell factor (SCF)-dependent hyperproliferation and impaired differentiation of human colony-forming unit-erythroid (CFU-E) cells, which were reversed by a c-Kit inhibitor. We further show that this was due to increased phosphorylation of c-Kit accompanied by decreased expression of phosphatase SHP-1, a negative regulator of c-Kit. At later stages, TET2 deficiency led to an accumulation of a progenitor population, which expressed surface markers characteristic of normal CFU-E cells but were functionally different. In contrast to normal CFU-E cells that require only erythropoietin (EPO) for proliferation, these abnormal progenitors required SCF and EPO and exhibited impaired differentiation. We termed this population of progenitors "marker CFU-E" cells. We further show that AXL expression was increased in marker CFU-E cells and that the increased AXL expression led to increased activation of AKT and ERK. Moreover, the altered proliferation and differentiation of marker CFU-E cells were partially rescued by an AXL inhibitor. Our findings document an important role for TET2 in erythropoiesis and have uncovered previously unknown mechanisms by which deficiency of TET2 contributes to ineffective erythropoiesis.

Adducin-1 is essential for spindle pole integrity through its interaction with TPX2.

Bipolar spindle assembly is necessary to ensure the proper progression of cell division. Loss of spindle pole integrity leads to multipolar spindles and aberrant chromosomal segregation. However, the mechanism underlying the maintenance of spindle pole integrity remains unclear. In this study, we show that the actin-binding protein adducin-1 (ADD1) is phosphorylated at S726 during mitosis. S726-phosphorylated ADD1 localizes to centrosomes, wherein it organizes into a rosette-like structure at the pericentriolar material. ADD1 depletion causes centriole splitting and therefore results in multipolar spindles during mitosis, which can be restored by re-expression of ADD1 and the phosphomimetic S726D mutant but not by the S726A mutant. Moreover, the phosphorylation of ADD1 at S726 is crucial for its interaction with TPX2, which is essential for spindle pole integrity. Together, our findings unveil a novel function of ADD1 in maintaining spindle pole integrity through its interaction with TPX2.

Cytokine and Growth Factor Delivery from Implanted Platelet-Rich Fibrin Enhances Rabbit Achilles Tendon Healing.

Tendons are hypocellular and hypovascular tissues, and thus, their natural healing capacity is low. In this study, we sought to evaluate the efficacy of platelet-rich fibrin (PRF) to serve as a bioactive scaffold in promoting the healing of rabbit Achilles tendon injury. For in vitro study, the essence portion of PRF was determined through bioluminescent assay. Furthermore, we analyzed the time-sequential cytokines-release kinetics of PRF and evaluated their effects on tenocytes proliferation and tenogenic gene expressions. In animal study, the rabbit Achilles tendon defect was left untreated or implanted with normal/heat-denatured PRF scaffolds. Six weeks postoperatively, the specimens were evaluated through sonographic imaging and histological analysis. The results revealed significantly more activated platelets on bottom half of the PRF scaffold. Cytokine concentrations released from PRF could be detected from the first hour to six days. For the in vitro study, PRF enhanced cell viability and collagen I, collagen III, tenomodulin, and tenascin gene expression compared to the standard culture medium. For in vivo study, sonographic images revealed significantly better tendon healing in the PRF group in terms of tissue echogenicity and homogeneity. The histological analysis showed that the healing tissues in the PRF group had more organized collagen fiber, less vascularity, and minimal cartilage formation. In conclusion, bioactive PRF promotes in vitro tenocytes viability and tenogenic phenotypic differentiation. Administration of a PRF scaffold at the tendon defect promotes tissue healing as evidenced by imaging and histological outcomes.