Vascularized acellular dermal matrix island flaps for the repair of abdominal muscle defects

The potential widespread use of tissue-engineered matrices in soft-tissue reconstruction has been limited by the difficulty in fabricating and confirming a functional microcirculation. Acellular dermal matrix placed in a soft-tissue pocket acts as a scaffold to be incorporated by the host's fibrovascular tissue. A new method for noninvasive real-time observation of functional microvascular networks using orthogonal polarization spectral (OPS) imaging has recently been reported. Arterioles, venules, and capillaries can be directly visualized, and the movement of individual blood cells through them can be observed. The present study was performed to investigate the use of prefabricated acellular dermal matrix with an arteriovenous unit for the repair of abdominal muscle defects. OPS imaging was used to determine the presence of a functional microcirculation in the neovascularized matrix. In Sprague-Dawley rats, vascularized matrix was prefabricated by placing the superficial epigastric artery and vein on a 2-cm x 2-cm implant-type acellular dermal matrix in the thigh. Three weeks after implantation, the matrix-arteriovenous unit was elevated as an axial-type flap and a 2-cm x 2-cm full-thickness block of abdominal muscle immediately superior to the inguinal ligament was resected. Additional procedures were performed according to group: no repair (group 1, n = 20); repair with nonvascularized acellular dermal matrix (group 2, n = 20); repair with devascularized acellular dermal matrix (group 3, = 20); and repair with vascularized acellular dermal matrix (group 4, n = 20). OPS imaging (field of view, 1 mm in diameter; scan depth range, 0.2 mm) was performed on both sides of each flap on a total of 10 random distal regions before and after pedicle transection in group 3 and with the pedicle preserved in group 4. Hernia rate and duration of survival were compared for 21 days. OPS imaging showed directional blood cell movement through the capillary network in all areas scanned in group 4. No microvascular perfusion was observed after pedicle transection in group 3. Hernia rates of 100, 80, 90, and 0 percent were seen in groups 1, 2, 3, and 4, respectively. Median survival times of 9, 11.5, 9, and 21 postoperative days were noted in groups 1, 2, 3, and 4, respectively. Histopathologic analysis with factor VIII revealed full-thickness infiltration of the matrix by endothelial cells, signifying newly formed blood vessels. Repair of abdominal muscle defects using vascularized acellular dermal matrix resulted in no hernia and survival of all animals for the duration of study. However, repairs using avascular or devascularized matrix resulted in significant rates of hernia and decreased survival. Acellular dermal matrix can be prefabricated into vascularized tissue using an arteriovenous unit and used successfully to repair abdominal muscle defects. OPS imaging allowed for high-contrast direct visualization of microcirculation in previously acellular tissue following prefabrication with an arteriovenous unit.     

Experimental assessment of the revascularization of acellular human dermis for soft-tissue augmentation

The purpose of this experimental study was to determine whether acellular human dermis was capable of complete revascularization in a subcutaneous implantation site with various placement geometries. In young adult rabbit ears, four different sheet and rolled configurations were placed and harvested after 3, 7, 14, and 28 days with silicone rubber microangiographic injections followed by histologic analysis. Revascularization of single-layer acellular human dermis occurred rapidly and was essentially complete by 14 days after surgery. No differences were observed in the ingrowth of vessels regardless of how the basement membrane was oriented. In rolled configurations, vascular ingrowth throughout the implant was slower and had not completely penetrated the grafts by 28 days after surgery at study completion. Vessel ingrowth occurred through the implant surfaces contacting the surrounding soft tissue and along the open seam of the roll. No differences were seen whether the basement membrane was oriented on either the inside or the outside of the roll. Acellular human dermis is capable of significant revascularization of its compact collagen composition in the early postoperative period. In thicker geometries, the rate and completeness of vessel ingrowth are predictably slower. Whether complete revascularization of multilayered or rolled grafts is achieved cannot be determined from this study.     

Comparison of two porcine-derived materials for repairing abdominal wall defects in rats

Objective

The purpose of this study was to compare the mechanical properties, host responses and incorporation of porcine small intestine submucosa (PSIS) and porcine acellular dermal matrix (PADM) in a rat model of abdominal wall defect repair.

Materials and Methods

Prior to implantation, PSIS and PADM were prepared and evaluated in terms of structure and mechanical properties. Full-thickness abdominal wall defects were created in 50 Sprague-Dawley rats, and were repaired using either PSIS or PADM. Rats were sacrificed 1, 2, 4, 8 and 12 weeks post-repair and examined for herniation, infection, adhesions, contraction, and changes in the thickness and strength of the tissues incorporated at the defect sites. Histopathology and immunohistochemistry were performed to analyze inflammatory responses, collagen deposition and vascularization.

Results

PADM showed more dense collagen deposition and stronger mechanical properties than PSIS prior to implantation (P<0.01). However, the mechanical properties observed after integration with the surrounding native tissues was similar for PADM and PSIS. Both PADM and PSIS showed significant contraction by week 12. However, PADM tissue induced less adhesion and increased in thickness more slowly, and showed less infiltration by foreign giant cells, polymorphonuclear cells, and mononuclear cells. Improved remodeling of host tissue was observed after PSIS implantation, which was apparent from the orientation of bands of fibrous connective tissue, intermixed with newly formed blood vessels by Week 12.

Conclusion

PSIS showed weaker mechanical properties prior to implantation. However, after implantation PSIS induced more pronounced host responses and showed better incorporation into host tissues than PADM.     

Rapid, easy, and cheap randomization: prospective evaluation in a study cohort

Background

Incisional hernia is a frequent complication in abdominal surgery. This article describes the development of a prospective randomized clinical trial designed to determine whether watchful waiting is an acceptable alternative to surgical repair for patients with oligosymptomatic incisional hernia.

Methods/Design

This clinical multicenter trial has been designed to compare watchful waiting and surgical repair for patients with oligosymptomatic incisional hernia. Participants are randomized to watchful waiting or surgery and followed up for two years. The primary efficacy endpoint is pain/discomfort during normal activities as a result of the hernia or hernia repair two years after enrolment, as measured by the hernia-specific Surgical Pain Scales (SPS). The target sample size of six hundred thirty-six patients was calculated to detect non-inferiority of the experimental intervention (watchful waiting) in the primary endpoint. Sixteen surgical centers will take part in the study and have submitted their declaration of commitment giving the estimated number of participating patients per year. A three-person data safety monitoring board will meet annually to monitor and supervise the trial.

Discussion

To date, we could find no published data on the natural course of incisional hernias. To our knowledge, watchful waiting has never been compared to standard surgical repair as a treatment option for incisional hernias. A trial to compare the outcome of the two approaches in patients with oligosymptomatic incisional hernias is urgently needed to provide data that can facilitate the choice between treatment options. If watchful waiting was equal to surgical repair, the high costs of surgical repair could be saved. The design for such a trial is described here. This multicenter trial will be funded by the German Research Foundation (DFG). The ethics committee of the Charité has approved the study protocol. Approval has been obtained from ten study sites at time of this submission. The electronic Case Report Forms have been created. The first patient was to be randomized November 14^th, 2011. An initiation meeting took place in Berlin January 9^th, 2012.

Trial Registration

ClinicalTrials.gov: NCT01349400     

Early results of vermilion lip augmentation using acellular allogeneic dermis: an adjunct in facial rejuvenation

The definitive approach to lip augmentation has yet to be defined. Herein is described a technique using acellular allogeneic dermal grafts that is easy, effective, and reproducible. Our results over the past 2 years include 47 patients (94 grafts). Three grafts to the upper lip have exhibited significant resorption, which warranted further augmentation. Early in the series, one graft was malpositioned too superiorly along the vermilion-cutaneous border. There have been no cases of infection, hematoma, or graft exposure. The overall complication rate was 4 percent (4 of 94). Our early results by using acellular allogeneic dermal grafts for lip augmentation are encouraging. Further studies are under way to better objectively define long-term results.     

Skeletal muscle tissue engineering approaches to abdominal wall hernia repair

Abdominal wall hernias resulting from prior incisions are a common surgical complication affecting hundreds of thousands of Americans each year. The negative consequences associated with abdominal hernias may be considerable, including pain, bowel incarceration, vascular disruption, organ loss, and death. Current clinical approaches for the treatment of abdominal wall hernias focus on the implantation of permanent biomaterial meshes or acellular xenografts. However, these approaches are not infrequently associated with postoperative infections, chronic sinuses, or small bowel obstruction. Furthermore, the most critical complication, hernia recurrence, has been well described and may occur in a large percentage of patients. Despite many advances in repair techniques, wound healing and skeletal muscle regeneration is limited in many cases, resulting in a decrease in abdominal wall tissue function and contributing to the high hernia recurrence rate. This review will give an overview of skeletal muscle anatomy, skeletal muscle regeneration, and herniation mechanisms, as well as discuss the current and future clinical solutions for abdominal wall hernia repair. Birth Defects Research (Part C) 84:315–321, 2008. © 2008 Wiley‐Liss, Inc.     

Granulocytic Leukemoid Reactions Associated with Malignant Disease

Large upper abdominal incisional hernias have always been a vexing problem to surgeons because of the rigidity of the costal arches.With the increasing longevity of our population and the constant improvement in ways to sustain older patients during operative procedures, incisional hernias, especially of the upper abdominal area, will undoubtedly become more prevalent.A new anatomical procedure for repair, which was used in 16 cases, eliminates the necessity of the use of various prosthetic materials: extrapleural sectioning of the costal cartilages from approximately the seventh to the tenth rib permits the directional pull of the attached musculature to narrow the defect, thus allowing repair of the hernia without tension.The procedure is technically a simple one and postoperative complications are minimal.     

The use of a subfascial vicryl mesh buttress to aid in the closure of massive ventral hernias following damage-control laparotomy

Damage control laparotomy for life-threatening abdominal conditions has gained wide acceptance in the management of exsanguinating trauma patients as well as septic patients with acute abdomen. Survivors considered too ill to undergo definitive abdominal wall closure are temporized, often with skin grafting on granulated viscera. These maneuvers compromise the integrity of the anterior abdominal wall and result in a subset of patients with loss of abdominal domain and massive, debilitating ventral hernias. A retrospective review was conducted of 21 such patients (16 men, five women) who underwent elective abdominal wall reconstruction at the Hospital of the University of Pennsylvania between November of 1998 and October of 2000. The purpose of this study was to report the authors' experience with these complex abdominal wall reconstructions. A double-layer, subfascial Vicryl mesh buttress was used in all repairs to aid in reestablishing abdominal wall integrity. The mean hernia size was 813 cm2 (range, 75 to 1836 cm2), and the average interval to definitive repair was 24.4 months (range, 3 weeks to 11 years). Mean follow-up was 13.5 months (range, 1 month to 40 months). Twenty patients (95 percent) had successful ventral hernia repair. Four patients with massive hernias (924 to 1836 cm2) required submuscular Marlex mesh implantation. Two patients (10 percent) developed abdominal compartment syndrome that required surgical decompression. One patient (5 percent) developed an incisional hernia at a prior colostomy site. Four patients (19 percent) had superficial skin dehiscence that healed secondarily with daily wound care. There were no mesh infections. In most cases, successful single-stage repair of large ventral hernias following damage control laparotomy can be achieved using a subfascial Vicryl mesh buttress in combination with other established reconstructive techniques. Massive defects exceeding 900 cm2 typically require permanent mesh implantation to achieve fascial closure and to minimize the risk of postoperative abdominal compartment syndrome and recurrent herniation. This technique represents an improved solution to a complicated problem and optimizes the aesthetic and functional outcome for these debilitated patients.     

Portable PET probes are a novel tool for intraoperative localization of tumor deposits

Background

The emergency treatment of incisional hernias is infrequent but it can be complicated with strangulation or obstruction and in some cases the surgical approach may also include an intestinal resection with the possibility of peritoneal contamination. Our study aims at reporting our experience in the emergency treatment of complicated incisional hernias.

Methods

Since January 1999 till July 2008, 89 patients (55 males and 34 females) were treated for complicated incisional hernias in emergency. The patients were divided in two groups: Group I consisting of 33 patients that were treated with prosthesis apposition and Group II, consisting of 56 patients that were treated by performing a direct abdominal wall muscles suture.

Results

All the patients underwent a 6-month follow up; we noticed 9 recurrences (9/56, 16%) in the patients treated with direct abdominal wall muscles suture and 1 recurrence (1/33, 3%) in the group of patients treated with the prosthesis apposition.

Conclusions

According to our experience, the emergency treatment of complicated incisional hernias through prosthesis apposition is always feasible and ensures less post-operative complications (16% vs 21,2%) and recurrences (3% vs 16%) compared to the patients treated with direct muscular suture.     

Restoration of abdominal wall integrity as a salvage procedure in difficult recurrent abdominal wall hernias using a method of wide myofascial release

The management of primary and recurrent giant incisional hernias remains a complex and frustrating challenge even with multiple alloplastic and autogenous closure options. The purpose of this study was to develop a reconstructive technique of restoring abdominal wall integrity to a subcategory of patients, who have failed initial hernia therapy, by performing superior and lateral myofascial release. Over a 1.5-year period, 10 patients with previously unsuccessful treatment of abdominal wall hernias, using either primary repair or placement of synthetic material, were studied. The patients had either recurrence of the hernia or complications such as infections requiring removal of synthetic material. The hernias were not able to be treated with standard primary closure techniques or synthetic material. The average defect size was 19 x 9 cm. Each patient underwent wide lysis of bowel adhesions releasing the posterior abdominal wall fascia to the posterior axillary line, subcutaneous release of the anterior abdominal wall fascia to a similar level, and complete removal of any synthetic material (if present). The abdominal domain was reestablished by releasing the laterally retracted abdominal wall. The amount of available abdominal wall tissue was increased by wide release of the cephalic abdominal wall fascia overlying the costal margin and the external oblique fascia and muscle laterally. If needed, partial thickness of the internal oblique muscle and its anterior fascia were also released laterally to perform a tension-free primary closure of the defect. All repairs were closed with satisfactory functional and aesthetic results. All alloplastic material was removed. Fascial release was limited so as to close only the hernia defect without tension. No significant release of the rectus sheath and muscle was needed. Good, dynamic muscle function was noted postoperatively. All repairs have remained intact, and no further abdominal wall hernias have been noted on follow-up.     

Biological incorporation of human acellular dermal matrix used in Achilles tendon repair

Human acellular dermal matrices (ADMs) are used successfully in a variety of procedures, including sports medicine related, wound repair, and breast reconstructions, but the mechanism of repair is still not fully understood. An opportunity to explore this mechanism presented itself when a patient experienced a rerupture of the native tendon due to a fall that occurred 2 months after undergoing an Achilles tendon repair using Matracell treated ADM. The ADM was removed and an extensive histology analysis was performed on the tissue. Additionally, a literature review was conducted to determine the mechanism of ADM integration into the tendon structure and explore if differences in this mechanism exist for different types of human ADMS. The histology analysis demonstrated that the healing process during a tendon reconstruction procedure is similar to that of wound healing. Furthermore, the literature review showed that differences exist in the mechanism for integration among various human ADMs and that these differences may be due to variances in the methods and technologies that manufactures use to process human ADMs.     

Incidence of Incisional Hernia after Cesarean Delivery: A Register-Based Cohort Study

Objective

To estimate the incidence of incisional hernias requiring surgical repair after cesarean delivery over a 10-year period.

Methods

This population- and register-based cohort study identified all women in Denmark with no history of previous abdominal surgery who had a cesarean delivery between 1991 and 2000. The cohort was followed from their first until 10 years after their last cesarean delivery within the inclusion period or until the first of the following events: hernia repair, death, emigration, abdominal surgery, or cesarean delivery after the inclusion period. For women who had a hernia repair, hospital records regarding the surgery and previous cesarean deliveries were tracked and manually analyzed to validate the relationship between hernia repair and cesarean delivery. Data were analyzed with a competing risk analysis that included each cesarean delivery.

Results

We identified 57,564 women who had had 68,271 cesarean deliveries during the inclusion period. During follow-up, 134 of these women had a hernia requiring repair. Of these 68 (51% [95% CI 42–60%]) were in a midline incision although the transverse incision was the primary approach at cesarean delivery during the inclusion period. The cumulated incidence of a hernia repair within 10 years after a cesarean delivery was 0.197% (95% CI 0.164–0.234%). The risk of a hernia repair was higher during the first 3 years after a cesarean delivery, with an incidence after 3 years of 0.157% (95% CI 0.127–0.187%).

Conclusions

The overall risk of an incisional hernia requiring surgical repair within 10 years after a cesarean delivery was 2 per 1000 deliveries in a population in which the transverse incision was the primary approach at cesarean delivery.     

Hernia fibroblasts lack β-estradiol induced alterations of collagen gene expression

Background  

Estrogens are reported to increase type I and type III collagen deposition and to regulate Metalloproteinase 2 (MMP-2) expression. These proteins are reported to be dysregulated in incisional hernia formation resulting in a significantly decreased type I to III ratio. We aimed to evaluate the β-estradiol mediated regulation of type I and type III collagen genes as well as MMP-2 gene expression in fibroblasts derived from patients with or without history of recurrent incisional hernia disease. We compared primary fibroblast cultures from male/female subjects without/without incisional hernia disease.     

Effects of diode laser therapy on the acellular dermal matrix

Acellular dermal matrix (ADM) was subcutaneously implanted into calvarian skin of male Wistar rats (n = 40). Low-level laser (λ 685 nm, 4 J/cm²) was locally applied in experimental group (n = 20) above the skin flap. Grafts were harvested at 1, 3, 7 and 14 days after surgery and underwent histological analyses. In treated animals, the extent of edema and the number of inflammatory cells were reduced (P < 0.05). The amount of collagen in graft treated with low-level laser were significantly higher than those of controls (P < 0.05) and were statistically more prominent on the 14th day after surgery. The mean count of fibroblasts was significantly higher in the low-laser therapy group within the 3rd day, showing a marked influx of fibroblasts into area. In conclusion, wound healing of the ADM appear to be positively affected by laser therapy.     

A Review of: “Alpha1 – Acid Glycoprotein (Genetics,Biochemistry, Physiological Functions and Pharmacology) P. Baumann,G.B. Eap,W.E. Müller,J.P. Tillement,Eds. Alan R. Liss,New York, 1989; hardbound, 470 pages, $94.00”

Abstract

Increasing complications in incisional hernia surgery call for novel treatments. A gene expression analysis of injured tissues displays important parameters for tissue regeneration. Until today, no reliable method has been described for a quantitative gene expression analysis of hernia tissues. In this work, a protocol is described for the isolation of DNA‐free total RNA of incisional hernias for the first time. Moreover, real‐time RT PCR assays for collagen type I and III and TGF‐β1 are demonstrated for relative gene expression analyses. Both methods enable relative gene expression analyses of hernia tissues for the first time.     

Total RNA-isolation of abdominal hernia of rats for quantitative real-time reverse transcription (RT) PCR assays

Increasing complications in incisional hernia surgery call for novel treatments. A gene expression analysis of injured tissues displays important parameters for tissue regeneration. Until today, no reliable method has been described for a quantitative gene expression analysis of hernia tissues. In this work, a protocol is described for the isolation of DNA-free total RNA of incisional hernias for the first time. Moreover, real-time RT PCR assays for collagen type I and III and TGF-beta1 are demonstrated for relative gene expression analyses. Both methods enable relative gene expression analyses of hernia tissues for the first time.     

Characterization of a new degradable polymer scaffold for regeneration of the dermis

Full thickness skin wounds in humans heal with scars, but without regeneration of the dermis. A degradable poly(urethane urea) scaffold (PUUR), Artelon^Ã?® is already used to reinforce soft tissues in orthopaedics, and for treatment of osteoarthritis of the hand, wrist, and foot. In this paper we have done in vitro experiments followed by in vivo studies to find out whether the PUUR is biocompatible and usable as a template for dermal regeneration. Human dermal fibroblasts were cultured on discs of PUUR, with different macrostructures (fibrous and porous). They adhered to and migrated into the scaffolds, and produced collagen. The porous scaffold was judged more suitable for clinical applications and 4 mm Ã?Â?, 2 mm-thick discs of porous scaffold (12% w/w or 9% w/w polymer solution) were inserted intradermally in four healthy human volunteers. The implants were well tolerated and increasing ingrowth of fibroblasts was seen over time in all subjects. The fibroblasts stained immunohistochemically for procollagen and von Willebrand factor, indicating neocollagenesis and angiogenesis within the scaffolds. The PUUR scaffold may be a suitable material to use as a template for dermal regeneration.     

High Incidence of Scrotal Hernias in a Closed Colony of FVB Mice

Although inguinal hernias are rarely reported to occur in mice, a high incidence of scrotal hernias was observed in a closed breeding colony of FVB/N mice. Unilateral or bilateral hernias occurred in more than 20% of the male mice in the colony that were available for necropsy over 3 inbred and 1 outcross generations; no female mice were affected. Organs commonly present within the hernial sac included the cecum and seminal vesicles. Hernias did not adversely affect the fertility or lifespan of the affected male mice. Although the condition was heritable, no clear pattern of transmission was evident.During development, the testes descend from the abdominal cavity through the inguinal canal and into the scrotum, guided by the processus vaginalis. In primates and carnivores, the processus vaginalis is largely or entirely obliterated during late gestation.¹³ When correct closure fails to occur, a hernial sac may travel through the deep inguinal ring to create an inguinal hernia.¹⁶ Protrusion of a hernial sac containing abdominal organs into the scrotum results in scrotal hernia, a severe and potentially dangerous form of inguinal hernia. In rodents, the inguinal canal is very short and the processus vaginalis remains patent throughout life, allowing the testes to pass freely between the scrotum and abdomen.¹³ Despite this potential pathway for herniation of abdominal organs, scrotal hernias have rarely been reported to occur in laboratory mice.Spontaneous inguinal hernias have rarely been reported in either male or female mice. Inguinal hernias occur in intact but not castrated male mice treated with estrogenic compounds and in intact female mice treated with testosterone or bearing testicular grafts.^1,2,10 Both male and female C57BL/6 mice that fail to express fibulin 3 develop multiple large hernias, including inguinal hernias.¹⁴ In these mice, herniation occurs at the myopectineal orifice, through the external inguinal ring. Female mice transgenic for insulin-like factor 3 develop inguinal hernias with 100% penetrance.¹¹ A recent report described a high incidence of lateral femoral hernias in an inbred colony of FVB/NHsd mice; the condition predominantly affected female mice.¹⁵ This phenomenon was attributed to genetic drift in a closed colony. We now report on another situation in which many hernias were noted in inbred FVB/N mice. In the present case, scrotal hernias occurred in a high proportion of FVB/N mice maintained in a closed breeding colony.     

Platelet gel supernatant as a potential tool to repopulate acellular heart valves

Objective

The aim of this study was to repopulate decellularized heart valve matrices with ovine mesenchymal stem cells (oMSCs) by the use of platelet gel (PG) supernatant, a storage vehicle for growth factors.

Methods

oMSCs were exposed to different concentrations of PG‐released supernatant and cell proliferation was evaluated using the MTS assay. oMSC motility and invasiveness were assayed using a Boyden chamber. A quantitative sandwich enzyme immunoassay was used to examine amounts of bFGF and TGF‐β1 in the PG supernatant. Repopulation of acellular heart valve matrices was stimulated by seeding matrices with oMSCs supplemented with the PG supernatant.

Results

The most significant increase in proliferation induced by PG supernatant appeared at 1 × 10⁵ plts/ml concentration. Higher concentrations evoked reduction of the stimulatory process. oMSC motility was most significantly stimulated at 1 × 10⁶ plts/ml. Stimulating invasiveness of oMSCs needed the much higher concentration of 2 × 10⁶ plts/ml. Immunoassays revealed that sheep PG supernatant contains 184.8 pg/ml bFGF and 60.5 ng/ml TGF‐β1. Moreover, repopulation of acellular heart valve matrices was significantly enhanced by PG supernatant addition and resulted in upregulation of the myofibroblast marker alpha‐smooth muscle actin.

Conclusions

Growth factors released from platelets had the potential to induce cell repopulation in a heart valve tissue engineering procedure, through stimulation of mesenchymal stem‐cell migration and invasion.     

Synthetic scaffold coating with adeno-associated virus encoding BMP2 to promote endogenous bone repair

Biomaterial scaffolds functionalized to stimulate endogenous repair mechanisms via the incorporation of osteogenic cues offer a potential alternative to bone grafting for the treatment of large bone defects. We first quantified the ability of a self-complementary adeno-associated viral vector encoding bone morphogenetic protein 2 (scAAV2.5-BMP2) to enhance human stem cell osteogenic differentiation in vitro. In two-dimensional culture, scAAV2.5-BMP2-transduced human mesenchymal stem cells (hMSCs) displayed significant increases in BMP2 production and alkaline phosphatase activity compared with controls. hMSCs and human amniotic-fluid-derived stem cells (hAFS cells) seeded on scAAV2.5-BMP2-coated three-dimensional porous polymer Poly(ε-caprolactone) (PCL) scaffolds also displayed significant increases in BMP2 production compared with controls during 12 weeks of culture, although only hMSC-seeded scaffolds displayed significantly increased mineral formation. PCL scaffolds coated with scAAV2.5-BMP2 were implanted into critically sized immunocompromised rat femoral defects, both with or without pre-seeding of hMSCs, representing ex vivo and in vivo gene therapy treatments, respectively. After 12 weeks, defects treated with acellular scAAV2.5-BMP2-coated scaffolds displayed increased bony bridging and had significantly higher bone ingrowth and mechanical properties compared with controls, whereas defects treated with scAAV2.5-BMP2 scaffolds pre-seeded with hMSCs failed to display significant differences relative to controls. When pooled, defect treatment with scAAV2.5-BMP2-coated scaffolds, both with or without inclusion of pre-seeded hMSCs, led to significant increases in defect mineral formation at all time points and increased mechanical properties compared with controls. This study thus presents a novel acellular bone-graft-free endogenous repair therapy for orthotopic tissue-engineered bone regeneration.