Aims. Biofilm-related infection is a major complication that occurs in orthopaedic surgery. Various treatments are available but efficacy to eradicate infections varies significantly. A systematic review was performed to evaluate therapeutic interventions combating biofilm-related infections on in vivo animal models. Methods. Literature research was performed on PubMed and Embase databases. Keywords used for search criteria were “bone AND biofilm”. Information on the species of the animal model, bacterial strain, evaluation of biofilm and bone infection, complications, key findings on observations, prevention, and treatment of biofilm were extracted. Results. A total of 43 studies were included. Animal models used included fracture-related infections (ten studies), periprosthetic joint infections (five studies), spinal infections (three studies), other implant-associated infections, and osteomyelitis. The most common bacteria were Staphylococcus species. Biofilm was most often observed with scanning electron microscopy. The natural history of biofilm revealed that the process of bacteria attachment, proliferation, maturation, and dispersal would take 14 days. For systemic mono-antibiotic therapy, only two of six studies using vancomycin reported significant biofilm reduction, and none reported eradication. Ten studies showed that combined systemic and topical antibiotics are needed to achieve higher biofilm reduction or eradication, and the effect is decreased with delayed treatment. Overall, 13 studies showed promising therapeutic potential with surface coating and antibiotic loading techniques. Conclusion. Combined topical and systemic application of antimicrobial agents effectively reduces biofilm at early stages. Future studies with sustained release of antimicrobial and biofilm-dispersing agents tailored to specific pathogens are warranted to achieve biofilm eradication. Cite this article: Bone Joint Res 2022;11(10):700–714

Introduction: Stress fractures comprise a major problem in female police or army recruits. The incidence of stress fractures is reported ranging from 3 to 10 fold when compared to male recruits taking the same training program. This study consisted of an intervention program aiming at reducing combat gear weight and locating the gear as close as possible to the body center of gravity. Material and Methods: In a prospective study we followed up two companies of female recruits of the Israel Border Police. Both companies were followed for the four months of basic training using a basic data questionnaire inclusive of previous physical activity habits, previous acute and overuse injuries, menstrual history and previous smoking habits. An injury questionnaire was filled on commencement of the course and every two weeks thereafter. The clinical records of medic and doctor visits, as well as the personal medical file, were revised. Roentgenological and scintigraphic imaging were performed during the course, when clinical suspicion of a stress fracture arose. The first company of 71 fighters used the standard combat gear amounting to 12.5 kg. The second company of 64 fighters used combat equipment weighing 9.4 kg, held in a combat girdle close to the body center of gravity, inclusive of a shorter personal combat riffle and personal combat vest. Results: There was no difference in the number of clinic visits between the two companies. Complaints suggesting stress fractures were recorded in the first company from the 3. rd. to the 8. th. week of training and in the second from the 1. st. to 3. rd. week. The percentage of fighters sent for Scintigraphy because of clinical suspicion of stress fractures was 22.5% in the first company and 6.25% in the second. The percentage of fighters in whom stress fractures were located by Scintigraphy was 15.5% in the first company and 4.7% in the second. The number of stress fractures in average per fighter was 0.45 fractures in the first company and 0.27 fractures in the second. When calculating only “dangerous” stress fractures (long bones and navicular) there were noted 0.34 fractures per fighter in the first company and 0.20 in the second. Total average training days lost for reason of stress fractures was 2.21 per fighter in the first company and 1.08 in the second. Conclusions: Reducing the weight of the fighting gear and securing it closer to the body center of gravity may have a positive effect in reducing the incidence of stress fractures in female recruits of fighting units during the intense basic training program

Peripheral nerve injuries (PNI) occur in 10% of combat casualties. In the immediate field-hospital setting, an insensate limb can affect the surgeon's assessment of limb viability and in the long-term PNI remain a source of considerable morbidity. Therefore the aims of this study are to document the recovery of combat PNI, as well as report on the effect of current medical management in improving functional outcome. In this study, we present the largest series of combat related PNI in Coalition troops since World War II. From May 2007 – May 2010, 100 consecutive patients (261 nerve injuries) were prospectively reviewed in a specialist PNI clinic. The functional recovery of each PNI was determined using the MRC grading classification (good, fair and poor). In addition, the incidence of neuropathic pain, the results of nerve grafting procedures, the return of plantar sensation, and the patients' current military occupational grading was recorded. At mean follow up 26.7 months, 175(65%) of nerve injuries had a good recovery, 57(21%) had a fair recovery and 39(14%) had a poor functional recovery. Neuropathic pain was noted in 33 patients, with Causalgia present in 5 cases. In 27(83%) patients, pain was resolved by medication, neurolysis or nerve grafting. In 35 cases, nerve repair was attempted at median 6 days from injury. Of these 62%(22) gained a good or fair recovery with 37%(13) having a poor functional result. Forty-two patients (47 limbs) initially presented with an insensate foot. At final follow up (mean 25.4 months), 89%(42 limbs) had a return of protective plantar sensation. Overall, 9 patients were able to return to full military duty (P2), with 45 deemed unfit for military service (P0 or P8). This study demonstrates that the majority of combat PNI will show some functional recovery. Adherence to the principles of war surgery to ensure that the wound is clear of infection and associated vascular and skeletal injuries are promptly treated will provide the optimal environment for nerve recovery. Although neuropathic pain affects a significant proportion of casualties, pharmacological and surgical intervention can alleviate the majority of symptoms. Finally, the presence of an insensate limb at initial surgery, should not be used as a marker of limb viability. The key to recovery of the PNI patient lies in a multi-disciplinary approach. Essential to this is regular surgical review to assess progress and to initiate prompt surgical intervention when needed. This approach allows early determination of prognosis, which is of huge value to the rehabilitating patient psychologically, and to the whole rehabilitation team

Objectives. The surgical challenge with severe hindfoot injuries is one of technical feasibility, and whether the limb can be salvaged. There is an additional question of whether these injuries should be managed with limb salvage, or whether patients would achieve a greater quality of life with a transtibial amputation. This study aims to measure functional outcomes in military patients sustaining hindfoot fractures, and identify injury features associated with poor function. Methods. Follow-up was attempted in all United Kingdom military casualties sustaining hindfoot fractures. All respondents underwent short-form (SF)-12 scoring; those retaining their limb also completed the American Academy of Orthopaedic Surgeons Foot and Ankle (AAOS F&A) outcomes questionnaire. A multivariate regression analysis identified injury features associated with poor functional recovery. Results. In 12 years of conflict, 114 patients sustained 134 fractures. Follow-up consisted of 90 fractures (90/134, 67%), at a median of five years (interquartile range (IQR) 52 to 80 months). The median Short-Form 12 physical component score (PCS) of 62 individuals retaining their limb was 45 (IQR 36 to 53), significantly lower than the median of 51 (IQR 46 to 54) in patients who underwent delayed amputation after attempted reconstruction (p = 0.0351). Regression analysis identified three variables associated with a poor F&A score: negative Bohler’s angle on initial radiograph; coexisting talus and calcaneus fracture; and tibial plafond fracture in addition to a hindfoot fracture. The presence of two out of three variables was associated with a significantly lower PCS compared with amputees (medians 29, IQR 27 to 43 vs 51, IQR 46 to 54; p < 0.0001). Conclusions. At five years, patients with reconstructed hindfoot fractures have inferior outcomes to those who have delayed amputation. It is possible to identify injuries which will go on to have particularly poor outcomes. Cite this article: P. M. Bennett, T. Stevenson, I. D. Sargeant, A. Mountain, J. G. Penn-Barwell. Outcomes following limb salvage after combat hindfoot injury are inferior to delayed amputation at five years. Bone Joint Res 2018;7:131–138. DOI: 10.1302/2046-3758.72.BJR-2017-0217.R2

Over 75% of combat casualties from Iraq and Afghanistan sustain injuries to the extremities, with 70% resulting from the effects of explosions. Damage to peripheral nerves may influence the surgical decision on limb viability in the short-term, as well as result in significant long-term disability. To date, there have been no reports of the incidence and severity of nerve injury in the current conflicts. A prospective assessment of United Kingdom (UK) Service Personnel attending a specialist nerve injury clinic was performed. For each patient the mechanism, level and severity of injury to the nerve was assessed and associated injuries were recorded. Fifty-six patients with 117 nerve injuries (median 2, range 1–5) were eligible for inclusion. This represents 12.9% of casualties sustaining an extremity injury. The most commonly injured nerves were the tibial (19%), common peroneal (16%) and ulnar nerves (16%). 25% (29) of nerve injuries were conduction block, 41% (48) axonotmesis and 34% (40) neurotmesis. The mechanism of injury did not affect the severity of injury sustained (explosion vs gunshot wound (GSW), p=0.53). An associated fracture was found in only 48% of nerve injuries and a vascular injury in 35%. The presence of an associated vascular injury resulted in more severe injuries (conduction vs axonotmesis and neurotmesis, p< 0.05). Nerves injured in association with a fracture, were more likely to develop axonotmesis (p< 0.05). The incidence of peripheral nerve injury from combat wounds is higher than previously reported. This may be related to increasing numbers of casualties surviving with complex extremity wounds. In a polytrauma situation, it may be difficult to assess a discrete peripheral neurological lesion. As only 35% of nerves injured are likely to have anatomical disruption, the presence of an intact nerve at initial surgery should not preclude the possibility of an injury. Therefore, serial examinations combined with appropriate neurophysiologic examination in the post-injury period are necessary to aid diagnosis and to allow timely surgical intervention. In addition, conduction block nerve injuries can be expected to make a full recovery. As this accounts for 25% of all nerve injuries, we recommend that the presence of an insensate extremity should not be used as an indicator for assessing limb viability

It is unclear whether combat casualties with complex hindfeet fractures would have an improved outcome with reconstruction or amputation. This study aimed to determine the outcomes of British military casualties sustaining calcaneal fractures. In the 12 years of conflict in Iraq and Afghanistan there were 116 calcaneal fractures in 98 patients. Seventy-four patients (74/98 76%) were contactable, providing follow up data for 85 fractures (85/116 73%). Median follow up was 5-years (64 months, IQR 52–79). Thirty limbs (30/85 35%) had undergone trans-tibial amputation at time of follow-up: there was no association between open fractures and requirement for amputation (p=0.06). Definitive treatment choice had a significant association with later requirement for amputation (p=0.0479). Fifty-two patients (52/74 70%) had been discharged from the military due to their injuries: there was a significant association between amputation and military discharge (p=0.001). Only 17 patients (17/74 23%) had been able to complete a military fitness test since their injury. The median physical component score of the SF-12 quality of life outcome tool for those undergoing amputation was 51.9 (IQR 48.1–54.3). The median for those retaining their limb was 44.1 (IQR 38.6–53.8). The difference between the two cohorts was not statistically significant (p=0.989)

We present the British Military's experience of treating devastating lower limb injuries in personnel returning from Iraq and Afghanistan. We evaluate current surgical practice of attempting to maximise stump length through sequential debridement, rather that early amputation outside the zone of injury. Following an observation that the frequency of sequential amputation had appeared to increase during spring 2009, it was speculated that there may be factors which would predict which patients would require a more aggressive early amputation. The Joint Theatre Trauma Registry was interrogated for all cases of amputation between Apr 06 and Sep 09. The following data were collected: demographics, mechanism of injury, requirement for massive transfusion, use of combat applied tourniquet, number of stump debridements and echelon of care performed at, all microbiology and final level of amputation. A regression analysis was performed to establish correlation between each data-set and final level of amputation. 95 cases were identified; 21 were either digits or upper limbs and excluded. Clinical notes of the remaining 74 cases were requested, of which 48 were available representing a total of 66 lower limb stumps. No significant relationships were established between sequential amputation and any of the variables we examined. It was not possible to identify factors with predictive value with respect to which patients would benefit from a more aggressive early amputation approach. These results support current practice by demonstrating that attempts to balance maximal stump length with sufficient debridement to eradicate infected tissue, does not expose patients to unnecessary operative “hits”

Introduction. We present the British Military's experience of treating devastating lower limb injuries in personnel returning from Iraq and Afghanistan. We evaluate current surgical practice of attempting to maximise stump length through sequential debridement, rather that early amputation outside the zone of injury. Following an observation that the frequency of sequential amputation had appeared to increase during spring 2009, it was speculated that there may be factors which would predict which patients would require a more aggressive early amputation. Methods. The Joint Theatre Trauma Registry was interrogated for all cases of amputation between April 2006 and September 2009. The following data were collected: demographics, mechanism of injury, requirement for massive transfusion, use of combat applied tourniquet, number of stump debridements and echelon of care performed, all microbiology and final level of amputation. A regression analysis was performed to establish correlation between each data-set and final level of amputation. Results. 95 cases were identified; 21 were either digits or upper limbs and excluded. Clinical notes of the remaining 74 cases were requested, of which 48 were available representing a total of 66 lower limb stumps. No significant relationships were established between sequential amputation and any of the variables we examined. It was not possible to identify factors with predictive value with respect to which patients would benefit from a more aggressive early amputation approach. Conclusions. These results support current practice by demonstrating that attempts to balance maximal stump length with sufficient debridement to eradicate infected tissue, does not expose patients to unnecessary operative ‘hits’

Topical Negative Pressure Therapy (TNPT) has gained increasing acceptance as a useful tool in wound management. Since 2002, the Royal Centre for Defence Medicine (RCDM) in South Birmingham has gained considerable experience with managing complex combat trauma with TNPT. The mainstay of managing high-energy combat wounds has changed little over the last century of conflict and remains early debridement, wound lavage, fracture stabilisation and delayed closure. Over the last 10 years the use of TNPT has proved to be a useful adjunct in promoting delayed primary and secondary closure, and is now common practise in the US and UK military medical services. There is however, little level 1 evidence to support the use of TNPT in military trauma. All military patients admitted to Selly Oak Hospital between April 2007 and March 2008 that were treated with TNPT were identified, those whose notes were available were included. 37 cases were included. There was a strong correlation between ISS, NISS, and antibiotic use during TNPT use and the total duration of secondary care. However, we found no correlation between delay to first TNPT application, the frequency or location of TNPT dressing changes and any of our surrogate markers of outcome. TNPT is just one of a number of techniques for managing military high-energy injuries and should not be seen as an alternative to the established principles. The high frequency of TNPT dressing changes is not supported by this research and this should be reflected in the clinical management of patients requiring prolonged TNPT

Blast and ballistic weapons used on the battlefield cause devastating injuries rarely seen outside armed conflict. These extremely high-energy injuries predominantly affect the limbs and are usually heavily contaminated with soil, foliage, clothing and even tissue from other casualties. Once life-threatening haemorrhage has been addressed, the military surgeon’s priority is to control infection.

Combining historical knowledge from previous conflicts with more recent experience has resulted in a systematic approach to these injuries. Urgent debridement of necrotic and severely contaminated tissue, irrigation and local and systemic antibiotics are the basis of management. These principles have resulted in successful healing of previously unsurvivable wounds. Healthy tissue must be retained for future reconstruction, vulnerable but viable tissue protected to allow survival and avascular tissue removed with all contamination.

While recent technological and scientific advances have offered some advantages, they must be judged in the context of a hard-won historical knowledge of these wounds. This approach is applicable to comparable civilian injury patterns. One of the few potential benefits of war is the associated improvement in our understanding of treating the severely injured; for this positive effect to be realised these experiences must be shared.

The Winston Churchill Memorial Trust was established in 1965 on Sir Winston's death as a national memorial and living tribute to him, and funded by many thousands of people who contributed to a public subscription. This now funds Travelling Fellowships to allow Churchill Fellows to travel abroad and learn lessons that can be brought back to benefit the local community and ultimately the UK as a whole. Both authors were recipients of this prestigious 2009 Fellowship in the category of “Treatment & Rehabilitation of Traumatic Injuries”. Over fifteen weeks we visited hospitals in Germany, Canada, and the USA with expertise in the early care, reconstruction and rehabilitation of the combat casualties of our NATO Allies. We aimed to learn lessons from their experience, exchange ideas and to make contacts. We visited the US military hospital in Landstuhl Regional Medical Center, Germany, the University of Alberta Hospital and Glenrose Rehabilitation Hospital and the two major centres of US military care at the Walter Reed Army Medical Center/National Naval Medical Center in Washington DC, and the Brooke Army Medical Center in San Antonio Texas. We present our experience from this Fellowship, some of the lessons we have learnt and the problems that we face in common with our NATO allies

This is a retrospective study examining the injury pattern, management and short-term outcomes of British Military casualties sustaining hindfoot fractures from the conflicts in Iraq and Afghanistan. In the 12-years of war, 114 patients sustained 134 hindfoot injuries. The calcaneus was fractured in 116 cases (87%): 54 (47%) were managed conservatively, with 30 (26%) undergoing internal fixation.

Eighteen-month follow-up was available for 92 patients (81%) and 114 hindfeet (85%). Nineteen patients (17%) required trans-tibial amputation in this time, with a further 17 (15%) requiring other revision surgery. Deep infection requiring surgical treatment occurred in 13 cases (11%) with S. aureus the commonest infective organism (46%). Deep infection was strongly associated with operative fracture management (p=0.0022). When controlling for multiple variables, the presence of deep infection was significantly associated with a requirement for amputation at 18 months (p=0.001). There was no association between open fractures and requirement for amputation at 18 months (p=0.926), nor was conservative management associated with amputation requirement (p=0.749).

The UK Military Trauma Registry was searched for all cases of primary bilateral lower limb amputation sustained over 6-years between March 2004 and March 2010. There were 1694 UK military patients injured or killed during this six-year study period.

Forty-three of these (2.8%) were casualties with bilateral lower limb amputations. All were men injured in Afghanistan by Improvised Explosive Devices. Six casualties were in vehicles when they were injured with the remaining 37 (80%) patrolling on foot. The mean New Injury Severity Score was 48.2 (SD 13.2). Nine patients also lost an upper limb (triple amputation); no patients survived loss of all four limbs. Six patients (14%) sustained an open pelvic fracture. Perineal/genital injury was a feature in 19 (44%) patients, ranging from unilateral orchidectomy to loss of genitalia and permanent requirement for colostomy and urostomy. The mean requirement for blood products was 66 units (SD=41.7). The minimum transfusion requirement was 8 units and the greatest was a patient requiring a total of 193 units of blood products.

Our findings detail the severe nature of these injuries together with the massive surgical and resuscitative efforts required to firstly keep patients alive and secondly reconstruct and prepare them for rehabilitation.

This study aimed to characterise severe open femoral fractures sustained by military personnel and to describe their orthopaedic management and preliminary outcomes. The UK Military Trauma Registry was searched for open femoral fractures sustained between 2006–2010. Clinical records and radiographs were reviewed and data gathered on demographics, injury, management and preliminary outcomes.

Thirty-four patients with 34 open femoral fractures were eligible for inclusion. The mean NISS was 22.4 (SD 12.28). Nineteen fractures were caused by gunshot wounds (56%), with the remainder due to blasts. Three patients (9%) suffered Grade 4 segmental bone loss. Intramedullary nailing was used in 22 patients (69%). A minimum of 12 month follow up was available for 33 patients (97%). Twenty-three patients (70%) had achieved fracture union within the first twelve months. One patient suffered deep infection requiring surgical debridement. Ten patients (30%) underwent a revision procedure due to femoral shortening or malunion: two required a transfemoral amputation. There was a significant association between bone loss and a poor outcome (revision surgery) at 12 months (p=0.00016). Infection rates were significantly lower in open femoral fractures when compared to similar published work on open tibial fractures (p=0.0257).

The TRISS methodology is used in by both the UK and US military trauma registries and relies on dividing casualties according to mechanism: penetrating or blunt. The UK and US military trauma registries use the original coefficients devised in 1987 and it is not clear how either registry analyses explosive casualties according to the TRISS methodology. This study aims to use the UK military trauma registry (JTTR) to calculate new TRISS coefficients for contemporary battlefield casualties injured by either gunshot or explosive mechanisms. The JTTR was searched for all UK Casualties injured or killed between 2003 and 2014. A logistic regression analysis was performed to devise new TRISS coefficients, these were then used to re-examine survival over the 12 years of the study. Comparing the predictions from the GSW TRISS model to the observed outcomes, it demonstrates a sensitivity of 98.1% and a specificity of 96.8% and an overall accuracy 97.8%. With respect to the explosive TRISS model, there is a sensitivity of 98.6%, a specificity of 97.4% and an overall accuracy of 98.4%. When this improved TRISS methodology was used to measure changes in survival, there was a sustained improvement over the 12-year study period.

The UK Military Trauma Registry was searched for all RN/RM personnel injured between March 2003 and April 2013. These records were then cross-referenced with the records of the Naval Service Medical Board of Survey which evaluates injured RN/RM personnel for medically discharge, continued service in a reduced capacity or return to full duty (RTD). Population at risk data was calculated from service records.

There were 277 casualties in the study period: 61 (22%) of these were fatalities; of the 216 survivors, 63 or 29% were medically discharged; 24 or 11% were placed in a reduced fitness category. A total of 129 individuals (46% of the total and 60% of survivors) returned to full duty. The greatest number of casualties was sustained in 2007; there was a 3% casualty risk per year of operational service between 2007–2013. The most common reason cited by the Naval Service medical board of survey for medical downgrading or discharge was injuries to the lower limb with upper limb trauma being the next most frequent injury.

This study characterises the injuries sustained by RN and RM personnel during recent conflicts and demonstrates significant challenge of predominantly orthopaedic injuries for reconstructive and rehabilitation services.

Traumatic amputations (TAs) are amongst the most significant orthopaedic sequelae following IED strikes. Biomechanically, longer residual limb length confers better function. However, post-trauma definitive through knee amputation (TKA) remains controversial.

UK military casualties sustaining ≥1 major TA, 01/08/2008–01/08/2010 were identified using the UK JTTR and post mortem CT databases. All through- and below-knee TAs were termed ‘potential TKAs’ (p-TKAs); hypothetical candidates for definitive TKA. We hypothesised that traumatic TKAs were more common than previously reported (4.5% of lower limb TAs) and a significant cohort of blast injuries exist suitable for definitive TKA.

146 cases (75 survivors, 71 fatalities) sustained 271 TAs (235 lower limb). TKA rate was 34/235 (14.2%). 63/130 survivor TAs and 66/140 fatality TAs merited analysis as p-TKAs. Detailed pathoanatomy was only available for fatality p-TKAs, for whom definitive TKA would have been proximal to the zone of injury (ZOI) in only 3/66 cases.

Blast-mediated traumatic TKAs are significantly more common than previously reported (p=0.0118). Most lower limb TAs are skeletally amenable to definitive TKA. Maximising stump length for function incurs the risks of definitive amputation within the original ZOI (including infection and heterotopic ossification) but proximal extent of blast soft tissue injury commonly makes this unavoidable.

Heterotopic ossification (HO) is perhaps the single most significant obstacle to independence, functional mobility, and return to duty for combat-injured veterans of Operation Enduring Freedom and Operation Iraqi Freedom. Recent research into the cause(s) of HO has been driven by a markedly higher prevalence seen in these wounded warriors than encountered in previous wars or following civilian trauma. To that end, research in both civilian and military laboratories continues to shed light onto the complex mechanisms behind HO formation, including systemic and wound specific factors, cell lineage, and neurogenic inflammation. Of particular interest, non-invasive in vivo testing using Raman spectroscopy may become a feasible modality for early detection, and a wound-specific model designed to detect the early gene transcript signatures associated with HO is being tested. Through a combined effort, the goals of early detection, risk stratification, and development of novel systemic and local prophylaxis may soon be attainable.

We live in troubled times. Increased opposition reliance on explosive devices, the widespread use of individual and vehicular body armour, and the improved survival of combat casualties have created many complex musculoskeletal injuries in the wars in Iraq and Afghanistan. Explosive mechanisms of injury account for 75% of all musculoskeletal combat casualties. Throughout all the echelons of care medical staff practice consistent treatment strategies of damage control orthopaedics including tourniquets, antibiotics, external fixation, selective amputations and vacuum-assisted closure. Complications, particularly infection and heterotopic ossification, remain frequent, and re-operations are common. Meanwhile, non-combat musculoskeletal casualties are three times more frequent than those derived from combat and account for nearly 50% of all musculoskeletal casualties requiring evacuation from the combat zone

Nanovesicle-based therapy is increasingly being pursued as a safe, cell-free strategy to combat various immunological, musculoskeletal and neurodegenerative diseases. Small secreted extracellular vesicles (sEVs) obtained from multipotent mesenchymal stromal cells (MSCs) are of particular interest for therapeutic use since they convey anti-inflammatory, anti-scarring and neuroprotective activities to the recipient cells. Cell-derived vesicles (CDVs) produced by a proprietary extrusion process are surrounded by a lipid bilayer membrane with correct membrane topology, display biological activities similar to MSC-derived EVs and may find specific application for organ-targeted drug delivery systems. Translation of nanovesicle-based therapeutics into clinical application requires quantitative and reproducible analysis of bioactivity and stability, and the potential for GMP-compliant manufacturing. Manufacturing and regulatory considerations as well as preclinical models to support clinical translation will be discussed