Safety Evaluation of ART352-L in Subjects Undergoing Posterolateral Spinal Fusion

Inclusion Criteria:

1. Male or female subjects ≥50 years of age scheduled to undergo single levelposterolateral lumbar spinal fusion surgery in conjunction with local autograft bonefor degenerative spondylolisthesis

2. Psychosocially, mentally, and physically able to fully comply with this protocolincluding the required follow-up visits, the filling out of required forms, and havethe ability to understand and give written informed consent

3. Willing and able to undergo diagnostic imaging, inclusive of X-rays and CT scans withcontrast

4. Persistent, disabling pain after at least 6 months of non-surgical intervention (e.g.,anti-inflammatory medication, physical therapy, chiropractic care) prior to providinginformed consent

5. Pre-operative Oswestry Disability Index (ODI) Score ≥30

6. Grade 1 or less spondylolisthesis or retrolisthesis

7. Absence of neurological motor deficit

8. Agree to use a highly reliable method of birth control (male and female subjects) forat least 90 days after administration of Investigational Product (IP) - Women ofchildbearing potential must have a negative pregnancy test at screening and again ≤7days prior to surgery. Perimenopausal women must be amenorrheic for at least 12 monthsprior to the time of providing informed consent to be considered of non-childbearingpotential.

9. Agree to remain nicotine-free for the duration of their participation in the study

Exclusion Criteria:

1. Multiple level spondylolistheses or a primary diagnosis of low back pain syndromesecondary to diseases other than degenerative spondylolisthesis

2. Concurrent medications that affect bone homeostasis including, but not limited to,bisphosphonates

3. Ongoing / existing infections in or around the surgical site or spine

4. Prior lumbar spine arthrodesis

5. Concurrent clinically significant autoimmune disorder or systemic inflammatory disease

6. Known hypersensitivity to recombinant Wnt proteins

7. Use of tobacco; subjects must be nicotine-free at screening and agree to remainnicotine free for the duration of the study

8. Use of medications that may impair cell proliferation and bone healing including:chemotherapy, radiation, chronic steroids and immunosuppressive drugs. Note:Medications that may impair cell proliferation are to be discussed with the protocolmedical monitor prior to enrollment

9. Severe established osteoporosis requiring active treatment e.g., with bone densitymore than 2.5 standard deviations below the young adult mean with one or moreosteoporotic fractures

10. A Body Mass index (BMI) ≥ 40 unless documentation clearly demonstrates why BMI is nota primary factor in the subject's decreased mobility

11. Chronic opioid use

12. History of deep vein thrombosis (DVT) or blood clotting abnormalities

13. Uncontrolled diabetes mellitus

14. Pre-operative/anesthesia evaluations deeming the subject ineligible for surgery

15. Female subjects who are pregnant or intend to become pregnant during the course of thestudy

16. Male subjects, if not infertile or surgically sterilized, who will not agree to usehighly-effective contraception or to not donate sperm from screening until at least 90days after receiving IP

17. Active malignancy ≤5 years prior to providing informed consent. EXCEPTIONS:Non-melanotic skin cancer, carcinoma-in-situ of the cervix. NOTE: If there is ahistory of prior malignancy, the subject must not be receiving other specifictreatment for their cancer.

18. Concurrent participation in another investigational drug, biologic or device studythat could confound study data

19. Involvement in or plans to engage in litigation or receiving Worker's Compensationrelated to neck, back, or leg pain