Nano-calcium silicate mineralized fish scale scaffolds for enhancing tendon-bone healing

Tendon-bone healing is essential for an effective rotator cuff tendon repair surgery,however,this remains a significant challenge due to the lack of biomaterials with high strength and bioactivity.Inspired by the high-performance exoskeleton of natural organisms,we set out to apply natural fish scale(FS)modified by calcium silicate nanoparticles(CS NPs)as a new biomaterial(CS-FS)to overcome the challenge.Benefit from its“Bouligand”microstructure,such FS-based scaffold maintained excellent tensile strength(125.05 MPa)and toughness(14.16 MJ/m^(3)),which are 1.93 and 2.72 times that of natural tendon respectively,allowing it to well meet the requirements for rotator cuff tendon repair.Additionally,CS-FS showed diverse bioactivities by stimulating the differentiation and phenotypic maintenance of multiple types of cells participated into the composition of tendon-bone junction,(e.g.bone marrow mesenchymal stem cells(BMSCs),chondrocyte,and tendon stem/progenitor cells(TSPCs)).In both rat and rabbit rotator cuff tear(RCT)models,CS-FS played a key role in the tendon-bone interface regeneration and biomechanical function,which may be achieved by activating BMP-2/Smad/Runx2 pathway in BMSCs.Therefore,natural fish scale-based biomaterials are the promising candidate for clinical tendon repair due to their outstanding strength and bioactivity.

Age-related secretion of grancalcin by macrophages induces skeletal stem/progenitor cell senescence during fracture healing

Skeletal stem/progenitor cell(SSPC)senescence is a major cause of decreased bone regenerative potential with aging,but the causes of SSPC senescence remain unclear.In this study,we revealed that macrophages in calluses secrete prosenescent factors,including grancalcin(GCA),during aging,which triggers SSPC senescence and impairs fracture healing.Local injection of human rGCA in young mice induced SSPC senescence and delayed fracture repair.Genetic deletion of Gca in monocytes/macrophages was sufficient to rejuvenate fracture repair in aged mice and alleviate SSPC senescence.Mechanistically,GCA binds to the plexin-B2 receptor and activates Arg2-mediated mitochondrial dysfunction,resulting in cellular senescence.Depletion of Plxnb2 in SSPCs impaired fracture healing.Administration of GCA-neutralizing antibody enhanced fracture healing in aged mice.Thus,our study revealed that senescent macrophages within calluses secrete GCA to trigger SSPC secondary senescence,and GCA neutralization represents a promising therapy for nonunion or delayed union in elderly individuals.

A Skin-Inspired Self-Adaptive System for Temperature Control During Dynamic Wound Healing

The thermoregulating function of skin that is capable of maintaining body temperature within a thermostatic state is critical.However,patients suffering from skin damage are struggling with the surrounding scene and situational awareness.Here,we report an interactive self-regulation electronic system by mimicking the human thermos-reception system.The skin-inspired self-adaptive system is composed of two highly sensitive thermistors(thermal-response composite materials),and a low-power temperature control unit(Laserinduced graphene array).The biomimetic skin can realize self-adjusting in the range of 35–42℃,which is around physiological temperature.This thermoregulation system also contributed to skin barrier formation and wound healing.Across wound models,the treatment group healed~10%more rapidly compared with the control group,and showed reduced inflammation,thus enhancing skin tissue regeneration.The skin-inspired self-adaptive system holds substantial promise for nextgeneration robotic and medical devices.

Progress of Transmural Healing in Crohn’s Disease

Recently transmural healing (TH) has become a subject of increasing interest as a potential therapeutic purpose for inflammatory bowel disease (IBD). Crohn’s disease (CD) is characterized by chronic inflammation of the gastrointestinal tract, which can involve any part of the digestive tract, and the lesions are usually discontinuous, with progressive and destructive transmural lesions that can lead to irreversible damage such as fibrotic strictures, complications such as fistulas and abscesses. Disease remission remains the primary goal of therapeutic management;however transmural healing is a very promising endpoint for monitoring treatment response. Along with small bowel imaging tests such as computed tomography scans Intestinal imaging (CTE), magnetic resonance intestinal imaging (MRE), intestinal ultrasound (IUS) and other related imaging technologies are popularized in CD diagnosis and treatment benefit. Transmural healing has been initially used in clinical practice and the correlation between its rules and long-term clinical remission has been explored.

Single-cell sequencing technology in diabetic wound healing:New insights into the progenitors-based repair strategies

Diabetes mellitus(DM),an increasingly prevalent chronic metabolic disease,is characterised by prolonged hyperglycaemia,which leads to long-term health consequences.Although much effort has been put into understanding the pathogenesis of diabetic wounds,the underlying mechanisms remain unclear.The advent of single-cell RNA sequencing(scRNAseq)has revolutionised biological research by enabling the identification of novel cell types,the discovery of cellular markers,the analysis of gene expression patterns and the prediction of develop-mental trajectories.This powerful tool allows for an in-depth exploration of pathogenesis at the cellular and molecular levels.In this editorial,we focus on progenitor-based repair strategies for diabetic wound healing as revealed by scRNAseq and highlight the biological behaviour of various healing-related cells and the alteration of signalling pathways in the process of diabetic wound healing.ScRNAseq could not only deepen our understanding of the complex biology of diabetic wounds but also identify and validate new targets for inter-vention,offering hope for improved patient outcomes in the management of this challenging complication of DM.

Impact of tibial transverse transport in tissue regeneration and wound healing with perspective on diabetic foot ulcers

In this editorial,we comment on an article by Liao et al published in the current issue of the World Journal of Diabetes.We focus on the clinical significance of tibial transverse transport(TTT)as an effective treatment for patients with diabetic foot ulcers(DFU).TTT has been associated with tissue regeneration,improved blood circulation,reduced amputation rates,and increased expression of early angiogenic factors.Mechanistically,TTT can influence macrophage polarization and growth factor upregulation.Despite this potential,the limitations and conflicting results of existing studies justify the need for further research into its optimal application and development.These clinical implications highlight the efficacy of TTT in recalcitrant DFU and provide lasting stimuli for tissue re-generation,and blood vessel and bone marrow improvement.Immunomodu-lation via systemic responses contributes to its therapeutic potential.Future studies should investigate the underlying molecular mechanisms to enhance our understanding and the efficacy of TTT.This manuscript emphasizes the potential of TTT in limb preservation and diabetic wound healing and suggests avenues for preventive measures against limb amputation in diabetes and peripheral artery disease.Here,we highlight the clinical significance of the TTT and its importance in healing DFU to promote the use of this technique in tissue regeneration.

Biological scaffold as potential platforms for stem cells:Current development and applications in wound healing

Wound repair is a complex challenge for both clinical practitioners and researchers.Conventional approaches for wound repair have several limitations.Stem cell-based therapy has emerged as a novel strategy to address this issue,exhibiting significant potential for enhancing wound healing rates,improving wound quality,and promoting skin regeneration.However,the use of stem cells in skin regeneration presents several challenges.Recently,stem cells and biomaterials have been identified as crucial components of the wound-healing process.Combination therapy involving the development of biocompatible scaffolds,accompanying cells,multiple biological factors,and structures resembling the natural extracellular matrix(ECM)has gained considerable attention.Biological scaffolds encompass a range of biomaterials that serve as platforms for seeding stem cells,providing them with an environment conducive to growth,similar to that of the ECM.These scaffolds facilitate the delivery and application of stem cells for tissue regeneration and wound healing.This article provides a comprehensive review of the current developments and applications of biological scaffolds for stem cells in wound healing,emphasizing their capacity to facilitate stem cell adhesion,proliferation,differentiation,and paracrine functions.Additionally,we identify the pivotal characteristics of the scaffolds that contribute to enhanced cellular activity.

ON101 Cream Increases the Wound Healing Rate in Diabetic Patients with Uremia—Cases Report

Diabetic patients who underwent long-term dialysis may increase the prevalence of foot ulceration. In addition, diabetic foot ulcer (DFUs) patients with end-stage renal disease (ESRD) do not heal well, and the amputation rate is 6.5 - 10 times higher compared to the non-nephropathic diabetic population. Thus, a suitable therapeutic agent was needed. ON101 is a topical cream that promotes diabetic wound healing through a unique macrophage-regulating ability. In this case series, we included 5 diabetes patients (mean age 54.6 ± 8.7 years, 4 mal) with ESRD (mean eGFR 7.4 ± 3.35 mL/min/1.73m2) and had experienced dialysis for at least 4.5 years. These patients also have UT (University of Texas) grade 2A DFUs that have existed for at least 1.5 months (mean ulcer duration 8.3 ± 8.97 months). These subjects were applied ON101 twice daily for up to 20 weeks, and wound size was recorded during treatment. Among these subjects, three ulcers (patient No. 1, 2, and 3) completely healed within 10 weeks upon ON101 application, and one ulcer was 99% reduced at 20th weeks (patient No. 4). Only one ulcer didn’t show an obvious response that may due to poor compliance in wound care and glucose control. In summary, the overall healing rate was 60%, suggesting ON101 performed equivalence healing efficacy in dialysis patients compared with those who did not have dialysis.

X-Paste improves wound healing in diabetes via NF-E2-related factor/HO-1 signaling pathway

BACKGROUND Diabetic foot ulcers(DFU),as severe complications of diabetes mellitus(DM),significantly compromise patient health and carry risks of amputation and mortality.AIM To offer new insights into the occurrence and development of DFU,focusing on the therapeutic mechanisms of X-Paste(XP)of wound healing in diabetic mice.METHODS Employing traditional Chinese medicine ointment preparation methods,XP combines various medicinal ingredients.High-performance liquid chromatography(HPLC)identified XP’s main components.Using streptozotocin(STZ)-induced diabetic,we aimed to investigate whether XP participated in the process of diabetic wound healing.RNA-sequencing analyzed gene expression differences between XP-treated and control groups.Molecular docking clarified XP’s treatment mechanisms for diabetic wound healing.Human umbilical vein endothelial cells(HUVECs)were used to investigate the effects of Andrographolide(Andro)on cell viability,reactive oxygen species generation,apoptosis,proliferation,and metastasis in vitro following exposure to high glucose(HG),while NF-E2-related factor-2(Nrf2)knockdown elucidated Andro’s molecular mechanisms.RESULTS XP notably enhanced wound healing in mice,expediting the healing process.RNA-sequencing revealed Nrf2 upregulation in DM tissues following XP treatment.HPLC identified 21 primary XP components,with Andro exhibiting strong Nrf2 binding.Andro mitigated HG-induced HUVECs proliferation,metastasis,angiogenic injury,and inflammation inhibition.Andro alleviates HG-induced HUVECs damage through Nrf2/HO-1 pathway activation,with Nrf2 knockdown reducing Andro’s proliferative and endothelial protective effects.CONCLUSION XP significantly promotes wound healing in STZ-induced diabetic models.As XP’s key component,Andro activates the Nrf2/HO-1 signaling pathway,enhancing cell proliferation,tubule formation,and inflammation reduction.

Understanding wound healing in obesity

Obesity has become more prevalent in the global population.It is associated with the development of several diseases including diabetes mellitus,coronary heart disease,and metabolic syndrome.There are a multitude of factors impacted by obesity that may contribute to poor wound healing outcomes.With millions worldwide classified as obese,it is imperative to understand wound healing in these patients.Despite advances in the understanding of wound healing in both healthy and diabetic populations,much is unknown about wound healing in obese patients.This review examines the impact of obesity on wound healing and several animal models that may be used to broaden our understanding in this area.As a growing portion of the population identifies as obese,understanding the underlying mechanisms and how to overcome poor wound healing is of the utmost importance.

Janus hydrogel/electrospun-membrane dressing enhancing wound healing in rats

Background:Excessive exudate secreted from chronic wounds often leads to overhydration and infection.Although a variety of dressings are currently available in clinical applications,they frequently fail to provide multifunction to promote chronic wound healing.The dressings with a Janus structure,featuring distinct properties on each side,are potential to improve wound healing.Methods:Composite dressings with a Janus structure were fabricated,comprising freeze-dried polycaprolactone(PCL)electrospun membrane and alginate-based hydrogel.The PCL fibrous membrane provided air permeability,while the hydrogel loaded with Deferoxamine,composed of alginate and poly(N-isopropylacrylamide)(PNIPAM),exhibited hygroscopic properties.The inclusion of PNIPAM imparted thermo-responsivity.Results:The hydrogel(thickness of 2.778±0.082 mm)exhibited a robust adhesion to the fiber membrane(thickness of 0.261±0.041 mm).For ANDC(Alginate-PNIPAM hydrogel with Deferoxamine/PCL membrane)samples,the water vapor transmission rate(WVTR)was measured to be 3364.80±23.23 g∙m−2∙day−1 and the swelling ratio at 2 h was determined to be 1179±125%.The thermo-responsivity of ANDC samples manifested in an increased swelling rate,escalating from 797±189%at 37°C to 1132±147%at 4°C.The elastic modulus was assessed for lyophilized and rehydrated ANDC sample.When theωof the rheometer rotor was decreased from 10 rad/s to 0.1 rad/s,the lyophilized dressing exhibited a decrease from 2.65±0.01 MPa to 1.80±0.90 MPa,while the rehydrated dressing demonstrated an increase from 133.65±55.68 Pa to 264.23±141.71 Pa.The pro-healing properties of the dressings were evaluated using full-thickness skin defect model on SD rats,and a circular wound of diameter 10 mm healed completely by day 12.Conclusion:The dressings not only protected the wound and absorbed excess exudate,but also demonstrated nondestructive peelability upon cooling,providing a novel approach for accelerating wound healing and management.

Antibacterial and angiogenic dual-functional fibrous membrane dressing for infected wound healing

Background:Skin,being a vital organ that regulates physiological responses in the human body,is prone to injury from external environmental factors.Healing full-thickness skin defects becomes especially challenging when infections and vascular injuries are involved.Traditional wound dressings with single functions,such as antibacterial or angiogenic properties,fall short in achieving rapid wound healing.To address this,there is a need to develop wound dressing materials that possess both effective antibacterial and angiogenic properties.Methods:In this study,we utilized electrospinning technology to fabricate hyaluronic acid-cellulose acetate fibrous membrane dressings,incorporating poly(ionic liquid)as an antibacterial polymer and deferoxamine as an angiogenic agent.Results:The resulting fibrous membrane dressing contained poly(ionic liquid)and deferoxamin showcased a microporous structure,drug-releasing capabilities,and excellent air permeability.It not only demonstrated highly effective antibacterial properties but also exhibited remarkable angiogenesis,thereby promoting the healing of full-thickness skin defect wounds in both in vitro and in vivo assays.Conclusion:These findings highlight the immense potential of this wound dressing material for future clinical applications.

Clinical Study on the Effectiveness of Xian Fang Huo Ming Yin for Treating Cutaneous Infections and Promoting Wound Healing in Patients with Perianal Abscess

Objective:To explore the effect of the Xian Fang Huo Ming Yin(XFHM)for treating cutaneous infections and promoting wound healing in patients with perianal abscesses.Methods:Sixty-one patients with perianal abscesses who were admitted to our hospital(Xinghua City People’s Hospital)from May 2022 to May 2023 were selected and randomly divided into two groups,a control group(30 cases)and a study group(31 cases).Both groups received surgical treatment.The control group received conventional treatment and warm water fumigation,sitz bath,and surgical dressing change after surgery,while the research group received XFHM based on the control group.XFHM was taken orally and replaced with warm water for fumigation and sitz bathing.Both groups received treatment for 4 weeks but discontinued sitz bathing after 2 weeks.Various clinical indicators between the two groups were compared.Results:The total clinical effective rate and wound recovery rate of the study group were higher than that of the control group.There were differences in the wound pain scores,surrounding tissue edema,and wound secretions at different time points.Both groups experienced wound pain.The scores of wound pain,surrounding tissue edema,and wound secretions of the study group were lower than those of the control group,7 and 14 days after surgery.The serum interleukin 6(IL-6),tumor necrosis factor-alpha(TNF-α)levels,and pH values of the study group were lower than those of the control group 10 days after surgery(P<0.05).Conclusion:The application of XFHM for treating cutaneous infections and promoting wound healing in patients with perianal abscesses improved the treatment outcome,alleviated clinical symptoms,and promoted healing.

Combination of graphene oxide and platelet-rich plasma improves tendon-bone healing in a rabbit model of supraspinatus tendon reconstruction

The treatment of rotator cuff tear is one of the major challenges for orthopedic surgeons.The key to treatment is the reconstruction of the tendon-bone interface(TBI).Autologous platelet-rich plasma(PRP)is used as a therapeutic agent to accelerate the healing of tendons,as it contains a variety of growth factors and is easy to prepare.Graphene oxide(GO)is known to improve the physical properties of biomaterials and promote tissue repair.In this study,PRP gels containing various concentrations of GO were prepared to promote TBI healing and supraspinatus tendon reconstruction in a rabbit model.The incorporation of GO improved the ultrastructure and mechanical properties of the PRP gels.The gels containing 0.5 mg/ml GO(0.5 GO/PRP)continuously released transforming growth factor-b1(TGF-b1)and platelet-derived growth factor(PDGF)-AB,and the released TGF-b1 and PDGF-AB were still at high concentrations,1063.451 pg/ml and814.217 pg/ml,respectively,on the 14th day.In vitro assays showed that the 0.5 GO/PRP gels had good biocompatibility and promoted bone marrow mesenchymal stem cells proliferation and osteogenic and chondrogenic differentiation.After 12 weeks of implantation,the magnetic resonance imaging,microcomputed tomography and histological results indicated that the newly regenerated tendons in the 0.5 GO/PRP group had a similar structure to natural tendons.Moreover,the biomechanical results showed that the newly formed tendons in the 0.5 GO/PRP group had better biomechanical properties compared to those in the other groups,and had more stable TBI tissue.Therefore,the combination of PRP and GO has the potential to be a powerful advancement in the treatment of rotator cuff injuries.

Metformin accelerates bone fracture healing by promoting type H vessel formation through inhibition of YAP1/TAZ expression

Due to increasing morbidity worldwide,fractures are becoming an emerging public health concern.This study aimed to investigate the effect of metformin on the healing of osteoporotic as well as normal fractures.Type H vessels have recently been identified as a bone-specific vascular subtype that supports osteogenesis.Here,we show that metformin accelerated fracture healing in both osteoporotic and normal mice.Moreover,metformin promoted angiogenesis in vitro under hypoxia as well as type H vessel formation throughout fracture healing.Mechanistically,metformin increased the expression of HIF-1α,an important positive regulator of type H vessel formation,by inhibiting the expression of YAP1/TAZ in calluses and hypoxia-cultured human microvascular endothelial cells(HMECs).The results of HIF-1αor YAP1/TAZ interference in hypoxia-cultured HMECs using si RNA further suggested that the enhancement of HIF-1αand its target genes by metformin is primarily through YAP1/TAZ inhibition.Finally,overexpression of YAP1/TAZ partially counteracted the effect of metformin in promoting type H vessel-induced angiogenesis-osteogenesis coupling during fracture repair.In summary,our findings suggest that metformin has the potential to be a therapeutic agent for fractures by promoting type H vessel formation through YAP1/TAZ inhibition.

Uncovering potential distinctive acoustic features of healing music

S Background Music therapy is a promising complementary intervention for addressing various mental health conditions.Despite evidence of the beneficial effects of music,the acoustic features that make music effective in therapeutic contexts remain elusive.Aims This study aimed to identify and validate distinctive acoustic features of healing music.Methods We constructed a healing music dataset(HMD)based on nominations from related professionals and extracted 370 acoustic features.Healing-distinctive acoustic features were identified as those that were(1)independent from genre within the HMD,(2)significantly different from music pieces in a classical music dataset(CMD)and(3)similar to pieces in a five-element music dataset(FEMD).We validated the identified features by comparing jazz pieces in the HMD with a jazz music dataset(JMD).We also examined the emotional properties of the features in a Chinese affective music system(CAMS).Results The HMD comprised 165 pieces.Among all the acoustic features,74.59%shared commonalities across genres,and 26.22%significantly differed between the HMD classical pieces and the CMD.The equivalence test showed that the HMD and FEMD did not differ significantly in 9.46%of the features.The potential healing-distinctive acoustic features were identified as the standard deviation of the roughness,mean and period entropy of the third coefficient of the mel-frequency cepstral coefficients.In a three-dimensional space defined by these features,HMD's jazz pieces could be distinguished from those of the JMD.These three features could significantly predict both subjective valence and arousal ratings in the CAMS.Conclusions The distinctive acoustic features of healing music that have been identified and validated in this study have implications for the development of artificial intelligence models for identifying therapeutic music,particularly in contexts where access to professional expertise may be limited.This study contributes to the growing body of research exploring the potential of digital technologies for healthcare interventions.

Mucosal healing and inflammatory bowel disease:Therapeutic implications and new targets

Mucosal healing(MH)is vital in maintaining homeostasis within the gut and protecting against injury and infections.Multiple factors and signaling pathways contribute in a dynamic and coordinated manner to maintain intestinal homeostasis and mucosal regeneration/repair.However,when intestinal homeostasis becomes chronically disturbed and an inflammatory immune response is constitutively active due to impairment of the intestinal epithelial barrier autoimmune disease results,particularly inflammatory bowel disease(IBD).Many proteins and signaling pathways become dysregulated or impaired during these pathological conditions,with the mechanisms of regulation just beginning to be understood.Consequently,there remains a relative lack of broadly effective therapeutics that can restore MH due to the complexity of both the disease and healing processes,so tissue damage in the gastrointestinal tract of patients,even those in clinical remission,persists.With increased understanding of the molecular mechanisms of IBD and MH,tissue damage from autoimmune disease may in the future be ameliorated by developing therapeutics that enhance the body’s own healing response.In this review,we introduce the concept of mucosal healing and its relevance in IBD as well as discuss the mechanisms of IBD and potential strategies for altering these processes and inducing MH.

Hypoxic Mesenchymal Stem Cells Promote Diabetic Wound Healing in Rats by Increasing VEGF Secretion

Diabetes mellitus is a global public health concern affecting an estimated 537 million people,and patients with diabetes are more susceptible to developing chronic wounds^([1,2]).The wound healing process is often affected by various factors,including infection,tissue hypoxia,necrosis,exudates,and excessive inflammatory cytokines^([3]).Presently,there is no effective treatment for refractory wound healing,and the development of new techniques and therapeutic strategies is urgently required for patients with diabetes who have chronic wounds.

Oral administration of Bifidobacterium breve improves anti-angiogenic drugs-derived oral mucosal wound healing impairment via upregulation of interleukin-10

Recent studies have suggested that long-term application of anti-angiogenic drugs may impair oral mucosal wound healing.This study investigated the effect of sunitinib on oral mucosal healing impairment in mice and the therapeutic potential of Bifidobacterium breve(B.breve).A mouse hard palate mucosal defect model was used to investigate the influence of sunitinib and/or zoledronate on wound healing.The volume and density of the bone under the mucosal defect were assessed by micro-computed tomography(micro-CT).Inflammatory factors were detected by protein microarray analysis and enzyme-linked immunosorbent assay(ELISA).The senescence and biological functions were tested in oral mucosal stem cells(OMSCs)treated with sunitinib.Ligated loop experiments were used to investigate the effect of oral B.breve.Neutralizing antibody for interleukin-10(IL-10)was used to prove the critical role of IL-10 in the pro-healing process derived from B.breve.Results showed that sunitinib caused oral mucosal wound healing impairment in mice.In vitro,sunitinib induced cellular senescence in OMSCs and affected biological functions such as proliferation,migration,and differentiation.Oral administration of B.breve reduced oral mucosal inflammation and promoted wound healing via intestinal dendritic cells(DCs)-derived IL-10.IL-10 reversed cellular senescence caused by sunitinib in OMSCs,and IL-10 neutralizing antibody blocked the ameliorative effect of B.breve on oral mucosal wound healing under sunitinib treatment conditions.In conclusion,sunitinib induces cellular senescence in OMSCs and causes oral mucosal wound healing impairment and oral administration of B.breve could improve wound healing impairment via intestinal DCs-derived IL-10.

Transcript shortening via alternative polyadenylation promotes gene expression during fracture healing

Maturation of the 3′end of almost all eukaryotic messenger RNAs(m RNAs)requires cleavage and polyadenylation.Most mammalian m RNAs are polyadenylated at different sites within the last exon,generating alternative polyadenylation(APA)isoforms that have the same coding region but distinct 3′untranslated regions(UTRs).The 3′UTR contains motifs that regulate m RNA metabolism;thus,changing the 3′UTR length via APA can significantly affect gene expression.Endochondral ossification is a central process in bone healing,but the impact of APA on gene expression during this process is unknown.Here,we report the widespread occurrence of APA,which impacts multiple pathways that are known to participate in bone healing.Importantly,the progression of endochondral ossification involves global 3′UTR shortening,which is coupled with an increased abundance of shortened transcripts relative to other transcripts;these results highlight the role of APA in promoting gene expression during endochondral bone formation.Our mechanistic studies of transcripts that undergo APA in the fracture callus revealed an intricate regulatory network in which APA enhances the expression of the collagen,type I,alpha 1(Col1a1)and Col1a2 genes,which encode the 2 subunits of the abundantly expressed protein collagen 1.APA exerts this effect by shortening the 3′UTRs of the Col1a1 and Col1a2 m RNAs,thus removing the binding sites of mi R-29a-3p,which would otherwise strongly promote the degradation of both transcripts.Taken together,our study is the first to characterize the crucial roles of APA in regulating the 3′UTR landscape and modulating gene expression during fracture healing.